* [PATCH] pstore: Fix uaf when backend is unregistered
@ 2024-09-29 12:43 Li XingYang
2024-09-29 12:47 ` Li XingYang
2024-09-30 13:12 ` Greg KH
0 siblings, 2 replies; 8+ messages in thread
From: Li XingYang @ 2024-09-29 12:43 UTC (permalink / raw)
To: kees, tony.luck, gpiccoli
Cc: linux-hardening, linux-kernel, Li XingYang, Zach Wade
when unload pstore_blk, we will unlink the pstore file and
set pos->dentry to NULL, but simple_unlink(d_inode(root), pos->dentry)
may free inode of pos->dentry and free pos by free_pstore_private,
this may trigger uaf. kasan report:
kernel: ==================================================================
kernel: BUG: KASAN: slab-use-after-free in pstore_put_backend_records+0x3a4/0x480
kernel: Write of size 8 at addr ffff8883efbe0390 by task modprobe/4308
kernel:
kernel: CPU: 1 PID: 4308 Comm: modprobe Kdump: loaded Not tainted 6.10.9-arch1-2 #2 5fd36c90225554e2cc88363729bd91e76130a89f
kernel: Hardware name: ASUS System Product Name/TUF GAMING X670E-PLUS, BIOS 3024 08/02/2024
kernel: Call Trace:
kernel: <TASK>
kernel: dump_stack_lvl+0x5d/0x80
kernel: print_report+0x174/0x505
kernel: ? __pfx__raw_spin_lock_irqsave+0x10/0x10
kernel: ? pstore_put_backend_records+0x3a4/0x480
kernel: kasan_report+0xd0/0x150
kernel: ? pstore_put_backend_records+0x3a4/0x480
kernel: pstore_put_backend_records+0x3a4/0x480
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: pstore_unregister+0x88/0x1b0
kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone 35171c701a99c31efe207b7a718dc583e4a6503a]
kernel: pstore_blk_exit+0x30/0x90 [pstore_blk 589d82101219208d8968e3adda9b96a2d42df635]
kernel: __do_sys_delete_module+0x350/0x560
kernel: ? __pfx___do_sys_delete_module+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __memcg_slab_free_hook+0x28e/0x470
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: do_syscall_64+0x82/0x190
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? do_syscall_64+0x8e/0x190
kernel: ? seq_read_iter+0x62f/0x1220
kernel: ? __x64_sys_openat+0x300/0x380
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? kasan_save_track+0x14/0x30
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? vfs_read+0x9a7/0xf00
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __audit_syscall_exit+0x38a/0x520
kernel: ? __pfx_vfs_read+0x10/0x10
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __audit_syscall_exit+0x38a/0x520
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __x64_sys_read+0x162/0x250
kernel: ? __pfx___x64_sys_read+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? syscall_exit_to_user_mode_prepare+0x148/0x170
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? do_syscall_64+0x8e/0x190
kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel: RIP: 0033:0x741f9d72946b
kernel: Code: 73 01 c3 48 8b 0d a5 c8 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 c8 0c 00 f7 d8 64 89 01 48
kernel: RSP: 002b:00007ffed7e621f8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
kernel: RAX: ffffffffffffffda RBX: 00006455e060ed30 RCX: 0000741f9d72946b
kernel: RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00006455e060ed98
kernel: RBP: 00007ffed7e62220 R08: 1999999999999999 R09: 0000000000000000
kernel: R10: 0000741f9d7a5fe0 R11: 0000000000000206 R12: 0000000000000000
kernel: R13: 00007ffed7e62250 R14: 0000000000000000 R15: 0000000000000000
kernel: </TASK>
kernel:
kernel: Allocated by task 3957:
kernel: kasan_save_stack+0x30/0x50
kernel: kasan_save_track+0x14/0x30
kernel: __kasan_kmalloc+0xaa/0xb0
kernel: pstore_mkfile+0x47e/0xbe0
kernel: pstore_get_backend_records+0x560/0x920
kernel: pstore_get_records+0xec/0x180
kernel: pstore_register+0x1c3/0x5a0
kernel: register_pstore_zone.cold+0x298/0x3d1 [pstore_zone]
kernel: pstore_blk_init+0x63c/0xff0 [pstore_blk]
kernel: do_one_initcall+0xa4/0x380
kernel: do_init_module+0x28a/0x7c0
kernel: load_module+0x7b57/0xb020
kernel: init_module_from_file+0xdf/0x150
kernel: idempotent_init_module+0x23c/0x780
kernel: __x64_sys_finit_module+0xbe/0x130
kernel: do_syscall_64+0x82/0x190
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel:
kernel: Freed by task 4308:
kernel: kasan_save_stack+0x30/0x50
kernel: kasan_save_track+0x14/0x30
kernel: kasan_save_free_info+0x3b/0x60
kernel: __kasan_slab_free+0x12c/0x1b0
kernel: kfree+0x198/0x3b0
kernel: evict+0x33d/0xab0
kernel: __dentry_kill+0x17f/0x590
kernel: dput+0x2d9/0x810
kernel: simple_unlink+0xf4/0x140
kernel: pstore_put_backend_records+0x271/0x480
kernel: pstore_unregister+0x88/0x1b0
kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone]
kernel: pstore_blk_exit+0x30/0x90 [pstore_blk]
kernel: __do_sys_delete_module+0x350/0x560
kernel: do_syscall_64+0x82/0x190
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel:
kernel: The buggy address belongs to the object at ffff8883efbe0380
which belongs to the cache kmalloc-64 of size 64
kernel: The buggy address is located 16 bytes inside of
freed 64-byte region [ffff8883efbe0380, ffff8883efbe03c0)
kernel:
kernel: The buggy address belongs to the physical page:
kernel: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3efbe0
kernel: memcg:ffff8883ef245801
kernel: flags: 0x2ffff8000000000(node=0|zone=2|lastcpupid=0x1ffff)
kernel: page_type: 0xffffefff(slab)
kernel: raw: 02ffff8000000000 ffff88810004c8c0 ffffea00043dcc40 dead000000000004
kernel: raw: 0000000000000000 0000000000200020 00000001ffffefff ffff8883ef245801
kernel: page dumped because: kasan: bad access detected
kernel:
kernel: Memory state around the buggy address:
kernel: ffff8883efbe0280: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ffff8883efbe0300: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
kernel: >ffff8883efbe0380: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ^
kernel: ffff8883efbe0400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ffff8883efbe0480: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
kernel: ==================================================================
kernel: Disabling lock debugging due to kernel taint
kernel: pstore: Unregistered pstore_blk as persistent store backend
kernel: ------------[ cut here ]------------
place the pos->dentry = NULL before simple_unlink(d_inode(root), pos->dentry)
Fixes: 609e28bb139e ("pstore: Remove filesystem records when backend is unregistered")
Signed-off-by: Li XingYang <lixingyang1@qq.com>
Signed-off-by: Zach Wade <zachwade.k@gmail.com>
---
fs/pstore/inode.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 56815799ce79..7561693e0f32 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -306,7 +306,7 @@ static struct dentry *psinfo_lock_root(void)
int pstore_put_backend_records(struct pstore_info *psi)
{
struct pstore_private *pos, *tmp;
- struct dentry *root;
+ struct dentry *root, *unlink_dentry;
root = psinfo_lock_root();
if (!root)
@@ -316,9 +316,10 @@ int pstore_put_backend_records(struct pstore_info *psi)
list_for_each_entry_safe(pos, tmp, &records_list, list) {
if (pos->record->psi == psi) {
list_del_init(&pos->list);
- d_invalidate(pos->dentry);
- simple_unlink(d_inode(root), pos->dentry);
+ unlink_dentry = pos->dentry;
pos->dentry = NULL;
+ d_invalidate(unlink_dentry);
+ simple_unlink(d_inode(root), unlink_dentry);
}
}
}
--
2.46.2
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] pstore: Fix uaf when backend is unregistered
2024-09-29 12:43 [PATCH] pstore: Fix uaf when backend is unregistered Li XingYang
@ 2024-09-29 12:47 ` Li XingYang
2024-09-30 13:12 ` Greg KH
1 sibling, 0 replies; 8+ messages in thread
From: Li XingYang @ 2024-09-29 12:47 UTC (permalink / raw)
To: kees, tony.luck, gpiccoli; +Cc: linux-hardening, linux-kernel, zachwade.k
On Sun, Sep 29, 2024 at 08:43:37PM +0800, Li XingYang wrote:
I have another idea to fix this issue, which is to no longer use pstore_put_mackend_records to release dentry, but instead to add the reference count of the pstore backend driver when mounting pstore using try_rodule_get to avoid uninstalling the backend driver during mounting, just like other file systems. However, it seems that a lot of things need to be changed.
> when unload pstore_blk, we will unlink the pstore file and
> set pos->dentry to NULL, but simple_unlink(d_inode(root), pos->dentry)
> may free inode of pos->dentry and free pos by free_pstore_private,
> this may trigger uaf. kasan report:
>
> kernel: ==================================================================
> kernel: BUG: KASAN: slab-use-after-free in pstore_put_backend_records+0x3a4/0x480
> kernel: Write of size 8 at addr ffff8883efbe0390 by task modprobe/4308
> kernel:
> kernel: CPU: 1 PID: 4308 Comm: modprobe Kdump: loaded Not tainted 6.10.9-arch1-2 #2 5fd36c90225554e2cc88363729bd91e76130a89f
> kernel: Hardware name: ASUS System Product Name/TUF GAMING X670E-PLUS, BIOS 3024 08/02/2024
> kernel: Call Trace:
> kernel: <TASK>
> kernel: dump_stack_lvl+0x5d/0x80
> kernel: print_report+0x174/0x505
> kernel: ? __pfx__raw_spin_lock_irqsave+0x10/0x10
> kernel: ? pstore_put_backend_records+0x3a4/0x480
> kernel: kasan_report+0xd0/0x150
> kernel: ? pstore_put_backend_records+0x3a4/0x480
> kernel: pstore_put_backend_records+0x3a4/0x480
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: pstore_unregister+0x88/0x1b0
> kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone 35171c701a99c31efe207b7a718dc583e4a6503a]
> kernel: pstore_blk_exit+0x30/0x90 [pstore_blk 589d82101219208d8968e3adda9b96a2d42df635]
> kernel: __do_sys_delete_module+0x350/0x560
> kernel: ? __pfx___do_sys_delete_module+0x10/0x10
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __memcg_slab_free_hook+0x28e/0x470
> kernel: ? __pfx___audit_syscall_exit+0x10/0x10
> kernel: do_syscall_64+0x82/0x190
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? do_syscall_64+0x8e/0x190
> kernel: ? seq_read_iter+0x62f/0x1220
> kernel: ? __x64_sys_openat+0x300/0x380
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? kasan_save_track+0x14/0x30
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? vfs_read+0x9a7/0xf00
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __audit_syscall_exit+0x38a/0x520
> kernel: ? __pfx_vfs_read+0x10/0x10
> kernel: ? __pfx___audit_syscall_exit+0x10/0x10
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __audit_syscall_exit+0x38a/0x520
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __pfx___audit_syscall_exit+0x10/0x10
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __x64_sys_read+0x162/0x250
> kernel: ? __pfx___x64_sys_read+0x10/0x10
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? syscall_exit_to_user_mode_prepare+0x148/0x170
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? do_syscall_64+0x8e/0x190
> kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
> kernel: RIP: 0033:0x741f9d72946b
> kernel: Code: 73 01 c3 48 8b 0d a5 c8 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 c8 0c 00 f7 d8 64 89 01 48
> kernel: RSP: 002b:00007ffed7e621f8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
> kernel: RAX: ffffffffffffffda RBX: 00006455e060ed30 RCX: 0000741f9d72946b
> kernel: RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00006455e060ed98
> kernel: RBP: 00007ffed7e62220 R08: 1999999999999999 R09: 0000000000000000
> kernel: R10: 0000741f9d7a5fe0 R11: 0000000000000206 R12: 0000000000000000
> kernel: R13: 00007ffed7e62250 R14: 0000000000000000 R15: 0000000000000000
> kernel: </TASK>
> kernel:
> kernel: Allocated by task 3957:
> kernel: kasan_save_stack+0x30/0x50
> kernel: kasan_save_track+0x14/0x30
> kernel: __kasan_kmalloc+0xaa/0xb0
> kernel: pstore_mkfile+0x47e/0xbe0
> kernel: pstore_get_backend_records+0x560/0x920
> kernel: pstore_get_records+0xec/0x180
> kernel: pstore_register+0x1c3/0x5a0
> kernel: register_pstore_zone.cold+0x298/0x3d1 [pstore_zone]
> kernel: pstore_blk_init+0x63c/0xff0 [pstore_blk]
> kernel: do_one_initcall+0xa4/0x380
> kernel: do_init_module+0x28a/0x7c0
> kernel: load_module+0x7b57/0xb020
> kernel: init_module_from_file+0xdf/0x150
> kernel: idempotent_init_module+0x23c/0x780
> kernel: __x64_sys_finit_module+0xbe/0x130
> kernel: do_syscall_64+0x82/0x190
> kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
> kernel:
> kernel: Freed by task 4308:
> kernel: kasan_save_stack+0x30/0x50
> kernel: kasan_save_track+0x14/0x30
> kernel: kasan_save_free_info+0x3b/0x60
> kernel: __kasan_slab_free+0x12c/0x1b0
> kernel: kfree+0x198/0x3b0
> kernel: evict+0x33d/0xab0
> kernel: __dentry_kill+0x17f/0x590
> kernel: dput+0x2d9/0x810
> kernel: simple_unlink+0xf4/0x140
> kernel: pstore_put_backend_records+0x271/0x480
> kernel: pstore_unregister+0x88/0x1b0
> kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone]
> kernel: pstore_blk_exit+0x30/0x90 [pstore_blk]
> kernel: __do_sys_delete_module+0x350/0x560
> kernel: do_syscall_64+0x82/0x190
> kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
> kernel:
> kernel: The buggy address belongs to the object at ffff8883efbe0380
> which belongs to the cache kmalloc-64 of size 64
> kernel: The buggy address is located 16 bytes inside of
> freed 64-byte region [ffff8883efbe0380, ffff8883efbe03c0)
> kernel:
> kernel: The buggy address belongs to the physical page:
> kernel: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3efbe0
> kernel: memcg:ffff8883ef245801
> kernel: flags: 0x2ffff8000000000(node=0|zone=2|lastcpupid=0x1ffff)
> kernel: page_type: 0xffffefff(slab)
> kernel: raw: 02ffff8000000000 ffff88810004c8c0 ffffea00043dcc40 dead000000000004
> kernel: raw: 0000000000000000 0000000000200020 00000001ffffefff ffff8883ef245801
> kernel: page dumped because: kasan: bad access detected
> kernel:
> kernel: Memory state around the buggy address:
> kernel: ffff8883efbe0280: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> kernel: ffff8883efbe0300: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
> kernel: >ffff8883efbe0380: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> kernel: ^
> kernel: ffff8883efbe0400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> kernel: ffff8883efbe0480: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
> kernel: ==================================================================
> kernel: Disabling lock debugging due to kernel taint
> kernel: pstore: Unregistered pstore_blk as persistent store backend
> kernel: ------------[ cut here ]------------
>
> place the pos->dentry = NULL before simple_unlink(d_inode(root), pos->dentry)
>
> Fixes: 609e28bb139e ("pstore: Remove filesystem records when backend is unregistered")
> Signed-off-by: Li XingYang <lixingyang1@qq.com>
> Signed-off-by: Zach Wade <zachwade.k@gmail.com>
> ---
> fs/pstore/inode.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
> index 56815799ce79..7561693e0f32 100644
> --- a/fs/pstore/inode.c
> +++ b/fs/pstore/inode.c
> @@ -306,7 +306,7 @@ static struct dentry *psinfo_lock_root(void)
> int pstore_put_backend_records(struct pstore_info *psi)
> {
> struct pstore_private *pos, *tmp;
> - struct dentry *root;
> + struct dentry *root, *unlink_dentry;
>
> root = psinfo_lock_root();
> if (!root)
> @@ -316,9 +316,10 @@ int pstore_put_backend_records(struct pstore_info *psi)
> list_for_each_entry_safe(pos, tmp, &records_list, list) {
> if (pos->record->psi == psi) {
> list_del_init(&pos->list);
> - d_invalidate(pos->dentry);
> - simple_unlink(d_inode(root), pos->dentry);
> + unlink_dentry = pos->dentry;
> pos->dentry = NULL;
> + d_invalidate(unlink_dentry);
> + simple_unlink(d_inode(root), unlink_dentry);
> }
> }
> }
> --
> 2.46.2
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] pstore: Fix uaf when backend is unregistered
2024-09-29 12:43 [PATCH] pstore: Fix uaf when backend is unregistered Li XingYang
2024-09-29 12:47 ` Li XingYang
@ 2024-09-30 13:12 ` Greg KH
2024-10-07 10:34 ` [PATCH v2] " Li XingYang
1 sibling, 1 reply; 8+ messages in thread
From: Greg KH @ 2024-09-30 13:12 UTC (permalink / raw)
To: Li XingYang
Cc: kees, tony.luck, gpiccoli, linux-hardening, linux-kernel, Zach Wade
On Sun, Sep 29, 2024 at 08:43:37PM +0800, Li XingYang wrote:
> when unload pstore_blk, we will unlink the pstore file and
> set pos->dentry to NULL, but simple_unlink(d_inode(root), pos->dentry)
> may free inode of pos->dentry and free pos by free_pstore_private,
> this may trigger uaf. kasan report:
>
> kernel: ==================================================================
> kernel: BUG: KASAN: slab-use-after-free in pstore_put_backend_records+0x3a4/0x480
> kernel: Write of size 8 at addr ffff8883efbe0390 by task modprobe/4308
> kernel:
> kernel: CPU: 1 PID: 4308 Comm: modprobe Kdump: loaded Not tainted 6.10.9-arch1-2 #2 5fd36c90225554e2cc88363729bd91e76130a89f
> kernel: Hardware name: ASUS System Product Name/TUF GAMING X670E-PLUS, BIOS 3024 08/02/2024
> kernel: Call Trace:
> kernel: <TASK>
> kernel: dump_stack_lvl+0x5d/0x80
> kernel: print_report+0x174/0x505
> kernel: ? __pfx__raw_spin_lock_irqsave+0x10/0x10
> kernel: ? pstore_put_backend_records+0x3a4/0x480
> kernel: kasan_report+0xd0/0x150
> kernel: ? pstore_put_backend_records+0x3a4/0x480
> kernel: pstore_put_backend_records+0x3a4/0x480
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: pstore_unregister+0x88/0x1b0
> kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone 35171c701a99c31efe207b7a718dc583e4a6503a]
> kernel: pstore_blk_exit+0x30/0x90 [pstore_blk 589d82101219208d8968e3adda9b96a2d42df635]
> kernel: __do_sys_delete_module+0x350/0x560
> kernel: ? __pfx___do_sys_delete_module+0x10/0x10
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __memcg_slab_free_hook+0x28e/0x470
> kernel: ? __pfx___audit_syscall_exit+0x10/0x10
> kernel: do_syscall_64+0x82/0x190
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? do_syscall_64+0x8e/0x190
> kernel: ? seq_read_iter+0x62f/0x1220
> kernel: ? __x64_sys_openat+0x300/0x380
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? kasan_save_track+0x14/0x30
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? vfs_read+0x9a7/0xf00
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __audit_syscall_exit+0x38a/0x520
> kernel: ? __pfx_vfs_read+0x10/0x10
> kernel: ? __pfx___audit_syscall_exit+0x10/0x10
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __audit_syscall_exit+0x38a/0x520
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __pfx___audit_syscall_exit+0x10/0x10
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? __x64_sys_read+0x162/0x250
> kernel: ? __pfx___x64_sys_read+0x10/0x10
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? syscall_exit_to_user_mode_prepare+0x148/0x170
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? do_syscall_64+0x8e/0x190
> kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: ? srso_alias_return_thunk+0x5/0xfbef5
> kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
> kernel: RIP: 0033:0x741f9d72946b
> kernel: Code: 73 01 c3 48 8b 0d a5 c8 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 c8 0c 00 f7 d8 64 89 01 48
> kernel: RSP: 002b:00007ffed7e621f8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
> kernel: RAX: ffffffffffffffda RBX: 00006455e060ed30 RCX: 0000741f9d72946b
> kernel: RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00006455e060ed98
> kernel: RBP: 00007ffed7e62220 R08: 1999999999999999 R09: 0000000000000000
> kernel: R10: 0000741f9d7a5fe0 R11: 0000000000000206 R12: 0000000000000000
> kernel: R13: 00007ffed7e62250 R14: 0000000000000000 R15: 0000000000000000
> kernel: </TASK>
> kernel:
> kernel: Allocated by task 3957:
> kernel: kasan_save_stack+0x30/0x50
> kernel: kasan_save_track+0x14/0x30
> kernel: __kasan_kmalloc+0xaa/0xb0
> kernel: pstore_mkfile+0x47e/0xbe0
> kernel: pstore_get_backend_records+0x560/0x920
> kernel: pstore_get_records+0xec/0x180
> kernel: pstore_register+0x1c3/0x5a0
> kernel: register_pstore_zone.cold+0x298/0x3d1 [pstore_zone]
> kernel: pstore_blk_init+0x63c/0xff0 [pstore_blk]
> kernel: do_one_initcall+0xa4/0x380
> kernel: do_init_module+0x28a/0x7c0
> kernel: load_module+0x7b57/0xb020
> kernel: init_module_from_file+0xdf/0x150
> kernel: idempotent_init_module+0x23c/0x780
> kernel: __x64_sys_finit_module+0xbe/0x130
> kernel: do_syscall_64+0x82/0x190
> kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
> kernel:
> kernel: Freed by task 4308:
> kernel: kasan_save_stack+0x30/0x50
> kernel: kasan_save_track+0x14/0x30
> kernel: kasan_save_free_info+0x3b/0x60
> kernel: __kasan_slab_free+0x12c/0x1b0
> kernel: kfree+0x198/0x3b0
> kernel: evict+0x33d/0xab0
> kernel: __dentry_kill+0x17f/0x590
> kernel: dput+0x2d9/0x810
> kernel: simple_unlink+0xf4/0x140
> kernel: pstore_put_backend_records+0x271/0x480
> kernel: pstore_unregister+0x88/0x1b0
> kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone]
> kernel: pstore_blk_exit+0x30/0x90 [pstore_blk]
> kernel: __do_sys_delete_module+0x350/0x560
> kernel: do_syscall_64+0x82/0x190
> kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
> kernel:
> kernel: The buggy address belongs to the object at ffff8883efbe0380
> which belongs to the cache kmalloc-64 of size 64
> kernel: The buggy address is located 16 bytes inside of
> freed 64-byte region [ffff8883efbe0380, ffff8883efbe03c0)
> kernel:
> kernel: The buggy address belongs to the physical page:
> kernel: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3efbe0
> kernel: memcg:ffff8883ef245801
> kernel: flags: 0x2ffff8000000000(node=0|zone=2|lastcpupid=0x1ffff)
> kernel: page_type: 0xffffefff(slab)
> kernel: raw: 02ffff8000000000 ffff88810004c8c0 ffffea00043dcc40 dead000000000004
> kernel: raw: 0000000000000000 0000000000200020 00000001ffffefff ffff8883ef245801
> kernel: page dumped because: kasan: bad access detected
> kernel:
> kernel: Memory state around the buggy address:
> kernel: ffff8883efbe0280: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> kernel: ffff8883efbe0300: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
> kernel: >ffff8883efbe0380: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> kernel: ^
> kernel: ffff8883efbe0400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> kernel: ffff8883efbe0480: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
> kernel: ==================================================================
> kernel: Disabling lock debugging due to kernel taint
> kernel: pstore: Unregistered pstore_blk as persistent store backend
> kernel: ------------[ cut here ]------------
>
> place the pos->dentry = NULL before simple_unlink(d_inode(root), pos->dentry)
>
> Fixes: 609e28bb139e ("pstore: Remove filesystem records when backend is unregistered")
> Signed-off-by: Li XingYang <lixingyang1@qq.com>
> Signed-off-by: Zach Wade <zachwade.k@gmail.com>
> ---
> fs/pstore/inode.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
Hi,
This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him
a patch that has triggered this response. He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created. Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.
You are receiving this message because of the following common error(s)
as indicated below:
- You have marked a patch with a "Fixes:" tag for a commit that is in an
older released kernel, yet you do not have a cc: stable line in the
signed-off-by area at all, which means that the patch will not be
applied to any older kernel releases. To properly fix this, please
follow the documented rules in the
Documentation/process/stable-kernel-rules.rst file for how to resolve
this.
If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.
thanks,
greg k-h's patch email bot
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v2] pstore: Fix uaf when backend is unregistered
2024-09-30 13:12 ` Greg KH
@ 2024-10-07 10:34 ` Li XingYang
0 siblings, 0 replies; 8+ messages in thread
From: Li XingYang @ 2024-10-07 10:34 UTC (permalink / raw)
To: gregkh, gpiccoli, kees, tony.luck
Cc: linux-hardening, linux-kernel, lixingyang1, zachwade.k, stable
when unload pstore_blk, we will unlink the pstore file and
set pos->dentry to NULL, but simple_unlink(d_inode(root), pos->dentry)
may free inode of pos->dentry and free pos by free_pstore_private,
this may trigger uaf. kasan report:
kernel: ==================================================================
kernel: BUG: KASAN: slab-use-after-free in pstore_put_backend_records+0x3a4/0x480
kernel: Write of size 8 at addr ffff8883efbe0390 by task modprobe/4308
kernel:
kernel: CPU: 1 PID: 4308 Comm: modprobe Kdump: loaded Not tainted 6.10.9-arch1-2 #2 5fd36c90225554e2cc88363729bd91e76130a89f
kernel: Hardware name: ASUS System Product Name/TUF GAMING X670E-PLUS, BIOS 3024 08/02/2024
kernel: Call Trace:
kernel: <TASK>
kernel: dump_stack_lvl+0x5d/0x80
kernel: print_report+0x174/0x505
kernel: ? __pfx__raw_spin_lock_irqsave+0x10/0x10
kernel: ? pstore_put_backend_records+0x3a4/0x480
kernel: kasan_report+0xd0/0x150
kernel: ? pstore_put_backend_records+0x3a4/0x480
kernel: pstore_put_backend_records+0x3a4/0x480
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: pstore_unregister+0x88/0x1b0
kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone 35171c701a99c31efe207b7a718dc583e4a6503a]
kernel: pstore_blk_exit+0x30/0x90 [pstore_blk 589d82101219208d8968e3adda9b96a2d42df635]
kernel: __do_sys_delete_module+0x350/0x560
kernel: ? __pfx___do_sys_delete_module+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __memcg_slab_free_hook+0x28e/0x470
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: do_syscall_64+0x82/0x190
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? do_syscall_64+0x8e/0x190
kernel: ? seq_read_iter+0x62f/0x1220
kernel: ? __x64_sys_openat+0x300/0x380
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? kasan_save_track+0x14/0x30
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? vfs_read+0x9a7/0xf00
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __audit_syscall_exit+0x38a/0x520
kernel: ? __pfx_vfs_read+0x10/0x10
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __audit_syscall_exit+0x38a/0x520
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __x64_sys_read+0x162/0x250
kernel: ? __pfx___x64_sys_read+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? syscall_exit_to_user_mode_prepare+0x148/0x170
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? do_syscall_64+0x8e/0x190
kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel: RIP: 0033:0x741f9d72946b
kernel: Code: 73 01 c3 48 8b 0d a5 c8 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 c8 0c 00 f7 d8 64 89 01 48
kernel: RSP: 002b:00007ffed7e621f8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
kernel: RAX: ffffffffffffffda RBX: 00006455e060ed30 RCX: 0000741f9d72946b
kernel: RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00006455e060ed98
kernel: RBP: 00007ffed7e62220 R08: 1999999999999999 R09: 0000000000000000
kernel: R10: 0000741f9d7a5fe0 R11: 0000000000000206 R12: 0000000000000000
kernel: R13: 00007ffed7e62250 R14: 0000000000000000 R15: 0000000000000000
kernel: </TASK>
kernel:
kernel: Allocated by task 3957:
kernel: kasan_save_stack+0x30/0x50
kernel: kasan_save_track+0x14/0x30
kernel: __kasan_kmalloc+0xaa/0xb0
kernel: pstore_mkfile+0x47e/0xbe0
kernel: pstore_get_backend_records+0x560/0x920
kernel: pstore_get_records+0xec/0x180
kernel: pstore_register+0x1c3/0x5a0
kernel: register_pstore_zone.cold+0x298/0x3d1 [pstore_zone]
kernel: pstore_blk_init+0x63c/0xff0 [pstore_blk]
kernel: do_one_initcall+0xa4/0x380
kernel: do_init_module+0x28a/0x7c0
kernel: load_module+0x7b57/0xb020
kernel: init_module_from_file+0xdf/0x150
kernel: idempotent_init_module+0x23c/0x780
kernel: __x64_sys_finit_module+0xbe/0x130
kernel: do_syscall_64+0x82/0x190
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel:
kernel: Freed by task 4308:
kernel: kasan_save_stack+0x30/0x50
kernel: kasan_save_track+0x14/0x30
kernel: kasan_save_free_info+0x3b/0x60
kernel: __kasan_slab_free+0x12c/0x1b0
kernel: kfree+0x198/0x3b0
kernel: evict+0x33d/0xab0
kernel: __dentry_kill+0x17f/0x590
kernel: dput+0x2d9/0x810
kernel: simple_unlink+0xf4/0x140
kernel: pstore_put_backend_records+0x271/0x480
kernel: pstore_unregister+0x88/0x1b0
kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone]
kernel: pstore_blk_exit+0x30/0x90 [pstore_blk]
kernel: __do_sys_delete_module+0x350/0x560
kernel: do_syscall_64+0x82/0x190
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel:
kernel: The buggy address belongs to the object at ffff8883efbe0380
which belongs to the cache kmalloc-64 of size 64
kernel: The buggy address is located 16 bytes inside of
freed 64-byte region [ffff8883efbe0380, ffff8883efbe03c0)
kernel:
kernel: The buggy address belongs to the physical page:
kernel: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3efbe0
kernel: memcg:ffff8883ef245801
kernel: flags: 0x2ffff8000000000(node=0|zone=2|lastcpupid=0x1ffff)
kernel: page_type: 0xffffefff(slab)
kernel: raw: 02ffff8000000000 ffff88810004c8c0 ffffea00043dcc40 dead000000000004
kernel: raw: 0000000000000000 0000000000200020 00000001ffffefff ffff8883ef245801
kernel: page dumped because: kasan: bad access detected
kernel:
kernel: Memory state around the buggy address:
kernel: ffff8883efbe0280: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ffff8883efbe0300: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
kernel: >ffff8883efbe0380: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ^
kernel: ffff8883efbe0400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ffff8883efbe0480: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
kernel: ==================================================================
kernel: Disabling lock debugging due to kernel taint
kernel: pstore: Unregistered pstore_blk as persistent store backend
kernel: ------------[ cut here ]------------
place the pos->dentry = NULL before simple_unlink(d_inode(root), pos->dentry)
Fixes: 609e28bb139e ("pstore: Remove filesystem records when backend is unregistered")
Cc: <stable@vger.kernel.org> # v5.8+
Signed-off-by: Li XingYang <lixingyang1@qq.com>
Signed-off-by: Zach Wade <zachwade.k@gmail.com>
---
fs/pstore/inode.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 56815799ce79..7561693e0f32 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -306,7 +306,7 @@ static struct dentry *psinfo_lock_root(void)
int pstore_put_backend_records(struct pstore_info *psi)
{
struct pstore_private *pos, *tmp;
- struct dentry *root;
+ struct dentry *root, *unlink_dentry;
root = psinfo_lock_root();
if (!root)
@@ -316,9 +316,10 @@ int pstore_put_backend_records(struct pstore_info *psi)
list_for_each_entry_safe(pos, tmp, &records_list, list) {
if (pos->record->psi == psi) {
list_del_init(&pos->list);
- d_invalidate(pos->dentry);
- simple_unlink(d_inode(root), pos->dentry);
+ unlink_dentry = pos->dentry;
pos->dentry = NULL;
+ d_invalidate(unlink_dentry);
+ simple_unlink(d_inode(root), unlink_dentry);
}
}
}
--
2.46.2
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] pstore: Fix uaf when backend is unregistered
2024-10-09 13:36 ` Zach Wade
@ 2024-10-15 14:45 ` Zach Wade
0 siblings, 0 replies; 8+ messages in thread
From: Zach Wade @ 2024-10-15 14:45 UTC (permalink / raw)
To: Kees Cook
Cc: tony.luck, gpiccoli, linux-hardening, linux-kernel, stable, lixingyang1
On 2024/10/9 21:36, Zach Wade wrote:
>
>
> On 2024/10/9 1:23, Kees Cook wrote:
>> On Wed, Oct 09, 2024 at 01:10:14AM +0800, Zach Wade wrote:
>>> when unload pstore_blk, we will unlink the pstore file and
>>> set pos->dentry to NULL, but simple_unlink(d_inode(root), pos->dentry)
>>> may free inode of pos->dentry and free pos by free_pstore_private,
>>> this may trigger uaf. kasan report:
>>
>> Thanks for this! I need to double check what happening here a bit more
>> closely, as maybe some ordering changed after a43e0fc5e913 ("pstore:
>> inode: Only d_invalidate() is needed")
>>
>>> @@ -316,9 +316,10 @@ int pstore_put_backend_records(struct
>>> pstore_info *psi)
>>> list_for_each_entry_safe(pos, tmp, &records_list, list) {
>>> if (pos->record->psi == psi) {
>>> list_del_init(&pos->list);
>>> - d_invalidate(pos->dentry);
>>> - simple_unlink(d_inode(root), pos->dentry);
>>> + unlink_dentry = pos->dentry;
>>> pos->dentry = NULL;
>>> + d_invalidate(unlink_dentry);
>>> + simple_unlink(d_inode(root), unlink_dentry);
>>
>> But on the face of it, this does solve the UAF. I'll double-check that
>> this isn't a result of the mentioned commit.
>
> Hi Cook,
>
> However, I think a more appropriate solution to the problem here is to
> check the reference count when uninstalling the mount point.
>
> At the same time, the test script is attached:
> #!/bin/bash
> modprobe pstore_blk
> blkdev=/dev/sda2
> best_effort=on
> mount -t pstore pstore /sys/fs/pstore
> sleep 2
> umount /sys/fs/pstore
> modprobe -r pstore_blk
>
> Thanks,
> Zach
>
>>
>
>> -Kees
>>
>
friendly ping.
Hi Cook,
How are you doing? I really hope we can solve this problem.
Thanks,
Zach
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] pstore: Fix uaf when backend is unregistered
2024-10-08 17:23 ` Kees Cook
@ 2024-10-09 13:36 ` Zach Wade
2024-10-15 14:45 ` Zach Wade
0 siblings, 1 reply; 8+ messages in thread
From: Zach Wade @ 2024-10-09 13:36 UTC (permalink / raw)
To: Kees Cook
Cc: tony.luck, gpiccoli, linux-hardening, linux-kernel, stable, lixingyang1
On 2024/10/9 1:23, Kees Cook wrote:
> On Wed, Oct 09, 2024 at 01:10:14AM +0800, Zach Wade wrote:
>> when unload pstore_blk, we will unlink the pstore file and
>> set pos->dentry to NULL, but simple_unlink(d_inode(root), pos->dentry)
>> may free inode of pos->dentry and free pos by free_pstore_private,
>> this may trigger uaf. kasan report:
>
> Thanks for this! I need to double check what happening here a bit more
> closely, as maybe some ordering changed after a43e0fc5e913 ("pstore:
> inode: Only d_invalidate() is needed")
>
>> @@ -316,9 +316,10 @@ int pstore_put_backend_records(struct pstore_info *psi)
>> list_for_each_entry_safe(pos, tmp, &records_list, list) {
>> if (pos->record->psi == psi) {
>> list_del_init(&pos->list);
>> - d_invalidate(pos->dentry);
>> - simple_unlink(d_inode(root), pos->dentry);
>> + unlink_dentry = pos->dentry;
>> pos->dentry = NULL;
>> + d_invalidate(unlink_dentry);
>> + simple_unlink(d_inode(root), unlink_dentry);
>
> But on the face of it, this does solve the UAF. I'll double-check that
> this isn't a result of the mentioned commit.
Hi Cook,
However, I think a more appropriate solution to the problem here is to
check the reference count when uninstalling the mount point.
At the same time, the test script is attached:
#!/bin/bash
modprobe pstore_blk
blkdev=/dev/sda2
best_effort=on
mount -t pstore pstore /sys/fs/pstore
sleep 2
umount /sys/fs/pstore
modprobe -r pstore_blk
Thanks,
Zach
>
> -Kees
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] pstore: Fix uaf when backend is unregistered
2024-10-08 17:10 [PATCH] " Zach Wade
@ 2024-10-08 17:23 ` Kees Cook
2024-10-09 13:36 ` Zach Wade
0 siblings, 1 reply; 8+ messages in thread
From: Kees Cook @ 2024-10-08 17:23 UTC (permalink / raw)
To: Zach Wade
Cc: tony.luck, gpiccoli, linux-hardening, linux-kernel, stable, lixingyang1
On Wed, Oct 09, 2024 at 01:10:14AM +0800, Zach Wade wrote:
> when unload pstore_blk, we will unlink the pstore file and
> set pos->dentry to NULL, but simple_unlink(d_inode(root), pos->dentry)
> may free inode of pos->dentry and free pos by free_pstore_private,
> this may trigger uaf. kasan report:
Thanks for this! I need to double check what happening here a bit more
closely, as maybe some ordering changed after a43e0fc5e913 ("pstore:
inode: Only d_invalidate() is needed")
> @@ -316,9 +316,10 @@ int pstore_put_backend_records(struct pstore_info *psi)
> list_for_each_entry_safe(pos, tmp, &records_list, list) {
> if (pos->record->psi == psi) {
> list_del_init(&pos->list);
> - d_invalidate(pos->dentry);
> - simple_unlink(d_inode(root), pos->dentry);
> + unlink_dentry = pos->dentry;
> pos->dentry = NULL;
> + d_invalidate(unlink_dentry);
> + simple_unlink(d_inode(root), unlink_dentry);
But on the face of it, this does solve the UAF. I'll double-check that
this isn't a result of the mentioned commit.
-Kees
--
Kees Cook
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] pstore: Fix uaf when backend is unregistered
@ 2024-10-08 17:10 Zach Wade
2024-10-08 17:23 ` Kees Cook
0 siblings, 1 reply; 8+ messages in thread
From: Zach Wade @ 2024-10-08 17:10 UTC (permalink / raw)
To: kees, tony.luck, gpiccoli
Cc: linux-hardening, linux-kernel, stable, lixingyang1, zachwade.k
when unload pstore_blk, we will unlink the pstore file and
set pos->dentry to NULL, but simple_unlink(d_inode(root), pos->dentry)
may free inode of pos->dentry and free pos by free_pstore_private,
this may trigger uaf. kasan report:
kernel: ==================================================================
kernel: BUG: KASAN: slab-use-after-free in
pstore_put_backend_records+0x3a4/0x480
kernel: Write of size 8 at addr ffff8883efbe0390 by task modprobe/4308
kernel:
kernel: CPU: 1 PID: 4308 Comm: modprobe Kdump: loaded Not tainted
6.10.9-arch1-2 #2 5fd36c90225554e2cc88363729bd91e76130a89f
kernel: Hardware name: ASUS System Product Name/TUF GAMING X670E-PLUS,
BIOS 3024 08/02/2024
kernel: Call Trace:
kernel: <TASK>
kernel: dump_stack_lvl+0x5d/0x80
kernel: print_report+0x174/0x505
kernel: ? __pfx__raw_spin_lock_irqsave+0x10/0x10
kernel: ? pstore_put_backend_records+0x3a4/0x480
kernel: kasan_report+0xd0/0x150
kernel: ? pstore_put_backend_records+0x3a4/0x480
kernel: pstore_put_backend_records+0x3a4/0x480
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: pstore_unregister+0x88/0x1b0
kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone
35171c701a99c31efe207b7a718dc583e4a6503a]
kernel: pstore_blk_exit+0x30/0x90 [pstore_blk
589d82101219208d8968e3adda9b96a2d42df635]
kernel: __do_sys_delete_module+0x350/0x560
kernel: ? __pfx___do_sys_delete_module+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __memcg_slab_free_hook+0x28e/0x470
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: do_syscall_64+0x82/0x190
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? do_syscall_64+0x8e/0x190
kernel: ? seq_read_iter+0x62f/0x1220
kernel: ? __x64_sys_openat+0x300/0x380
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? kasan_save_track+0x14/0x30
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? vfs_read+0x9a7/0xf00
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __audit_syscall_exit+0x38a/0x520
kernel: ? __pfx_vfs_read+0x10/0x10
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __audit_syscall_exit+0x38a/0x520
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __pfx___audit_syscall_exit+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? __x64_sys_read+0x162/0x250
kernel: ? __pfx___x64_sys_read+0x10/0x10
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? syscall_exit_to_user_mode_prepare+0x148/0x170
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? do_syscall_64+0x8e/0x190
kernel: ? syscall_exit_to_user_mode+0x73/0x1f0
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: ? srso_alias_return_thunk+0x5/0xfbef5
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel: RIP: 0033:0x741f9d72946b
kernel: Code: 73 01 c3 48 8b 0d a5 c8 0c 00 f7 d8 64 89 01 48 83 c8 ff
c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05
<48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 c8 0c 00 f7 d8 64 89 01 48
kernel: RSP: 002b:00007ffed7e621f8 EFLAGS: 00000206 ORIG_RAX:
00000000000000b0
kernel: RAX: ffffffffffffffda RBX: 00006455e060ed30 RCX: 0000741f9d72946b
kernel: RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00006455e060ed98
kernel: RBP: 00007ffed7e62220 R08: 1999999999999999 R09: 0000000000000000
kernel: R10: 0000741f9d7a5fe0 R11: 0000000000000206 R12: 0000000000000000
kernel: R13: 00007ffed7e62250 R14: 0000000000000000 R15: 0000000000000000
kernel: </TASK>
kernel:
kernel: Allocated by task 3957:
kernel: kasan_save_stack+0x30/0x50
kernel: kasan_save_track+0x14/0x30
kernel: __kasan_kmalloc+0xaa/0xb0
kernel: pstore_mkfile+0x47e/0xbe0
kernel: pstore_get_backend_records+0x560/0x920
kernel: pstore_get_records+0xec/0x180
kernel: pstore_register+0x1c3/0x5a0
kernel: register_pstore_zone.cold+0x298/0x3d1 [pstore_zone]
kernel: pstore_blk_init+0x63c/0xff0 [pstore_blk]
kernel: do_one_initcall+0xa4/0x380
kernel: do_init_module+0x28a/0x7c0
kernel: load_module+0x7b57/0xb020
kernel: init_module_from_file+0xdf/0x150
kernel: idempotent_init_module+0x23c/0x780
kernel: __x64_sys_finit_module+0xbe/0x130
kernel: do_syscall_64+0x82/0x190
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel:
kernel: Freed by task 4308:
kernel: kasan_save_stack+0x30/0x50
kernel: kasan_save_track+0x14/0x30
kernel: kasan_save_free_info+0x3b/0x60
kernel: __kasan_slab_free+0x12c/0x1b0
kernel: kfree+0x198/0x3b0
kernel: evict+0x33d/0xab0
kernel: __dentry_kill+0x17f/0x590
kernel: dput+0x2d9/0x810
kernel: simple_unlink+0xf4/0x140
kernel: pstore_put_backend_records+0x271/0x480
kernel: pstore_unregister+0x88/0x1b0
kernel: unregister_pstore_zone+0x2f/0xd0 [pstore_zone]
kernel: pstore_blk_exit+0x30/0x90 [pstore_blk]
kernel: __do_sys_delete_module+0x350/0x560
kernel: do_syscall_64+0x82/0x190
kernel: entry_SYSCALL_64_after_hwframe+0x76/0x7e
kernel:
kernel: The buggy address belongs to the object at ffff8883efbe0380
which belongs to the cache
kmalloc-64 of size 64
kernel: The buggy address is located 16 bytes inside of
freed 64-byte region
[ffff8883efbe0380, ffff8883efbe03c0)
kernel:
kernel: The buggy address belongs to the physical page:
kernel: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
pfn:0x3efbe0
kernel: memcg:ffff8883ef245801
kernel: flags: 0x2ffff8000000000(node=0|zone=2|lastcpupid=0x1ffff)
kernel: page_type: 0xffffefff(slab)
kernel: raw: 02ffff8000000000 ffff88810004c8c0 ffffea00043dcc40
dead000000000004
kernel: raw: 0000000000000000 0000000000200020 00000001ffffefff
ffff8883ef245801
kernel: page dumped because: kasan: bad access detected
kernel:
kernel: Memory state around the buggy address:
kernel: ffff8883efbe0280: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ffff8883efbe0300: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
kernel: >ffff8883efbe0380: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ^
kernel: ffff8883efbe0400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
kernel: ffff8883efbe0480: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
kernel: ==================================================================
kernel: Disabling lock debugging due to kernel taint
kernel: pstore: Unregistered pstore_blk as persistent store backend
kernel: ------------[ cut here ]------------
place the pos->dentry = NULL before simple_unlink(d_inode(root),
pos->dentry)
Fixes: 609e28bb139e ("pstore: Remove filesystem records when backend is
unregistered")
Signed-off-by: Li XingYang <lixingyang1@qq.com>
Signed-off-by: Zach Wade <zachwade.k@gmail.com>
---
fs/pstore/inode.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 56815799ce79..7561693e0f32 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -306,7 +306,7 @@ static struct dentry *psinfo_lock_root(void)
int pstore_put_backend_records(struct pstore_info *psi)
{
struct pstore_private *pos, *tmp;
- struct dentry *root;
+ struct dentry *root, *unlink_dentry;
root = psinfo_lock_root();
if (!root)
@@ -316,9 +316,10 @@ int pstore_put_backend_records(struct pstore_info *psi)
list_for_each_entry_safe(pos, tmp, &records_list, list) {
if (pos->record->psi == psi) {
list_del_init(&pos->list);
- d_invalidate(pos->dentry);
- simple_unlink(d_inode(root), pos->dentry);
+ unlink_dentry = pos->dentry;
pos->dentry = NULL;
+ d_invalidate(unlink_dentry);
+ simple_unlink(d_inode(root), unlink_dentry);
}
}
}
--
2.46.2
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2024-10-15 14:45 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-09-29 12:43 [PATCH] pstore: Fix uaf when backend is unregistered Li XingYang
2024-09-29 12:47 ` Li XingYang
2024-09-30 13:12 ` Greg KH
2024-10-07 10:34 ` [PATCH v2] " Li XingYang
2024-10-08 17:10 [PATCH] " Zach Wade
2024-10-08 17:23 ` Kees Cook
2024-10-09 13:36 ` Zach Wade
2024-10-15 14:45 ` Zach Wade
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