Re: [PATCH] static_call: Fix a wild-memory-access bug in static_call_del_module()

[Jinjie Ruan <ruanjinjie@huawei.com>]

Hi, it seems that this bug still exit.

On 2023/9/15 16:21, Jinjie Ruan wrote:
> Inject fault while probing btrfs.ko, if the first kzalloc() fails
> in __static_call_init(), key->mods will no be initialized. And then
> in static_call_del_module() the site_mod->mod will cause
> wild-memory-access as below:
> 
> So assign key->mods to NULL in __static_call_init() if it fails
> to fix the issue. And if kzalloc fails, it will just return in init
> func, so it should break if it the key->mods is NULL in exit func.
> 
>  general protection fault, probably for non-canonical address 0xeb800159c89f94a0: 0000 [#1] PREEMPT SMP KASAN
>  KASAN: maybe wild-memory-access in range [0x5c002ace44fca500-0x5c002ace44fca507]
>  CPU: 2 PID: 1843 Comm: modprobe Tainted: G        W        N 6.6.0-rc1+ #60
>  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
>  RIP: 0010:static_call_del_module+0x113/0x280
>  Code: 3c 20 00 0f 85 ef 00 00 00 49 8b 6e 08 48 85 ed 75 0d eb 75 48 85 db 74 70 49 89 ef 48 89 dd 48 8d 7d 08 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 75 78 48 89 e8 4c 8b 6d 08 48 c1 e8 03 42 80 3c 20
>  RSP: 0018:ffff888101d3f860 EFLAGS: 00010206
>  RAX: 0b800559c89f94a0 RBX: 5c002ace44fca4f8 RCX: ffffffffa0210f00
>  RDX: ffffffffa0210ed4 RSI: ffffffffa0210edc RDI: 5c002ace44fca500
>  RBP: 5c002ace44fca4f8 R08: 0000000000000000 R09: ffffed10233e4eea
>  R10: ffffed10233e4ee9 R11: ffff888119f2774b R12: dffffc0000000000
>  R13: 80002ace3cfca4f8 R14: ffffffff85196de0 R15: ffffffff84ee9f99
>  FS:  00007f4ff6faa540(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 00007ffc3d1f19e8 CR3: 0000000109fa6001 CR4: 0000000000170ee0
>  DR0: ffffffff8faefce8 DR1: ffffffff8faefce9 DR2: ffffffff8faefcea
>  DR3: ffffffff8faefceb DR6: 00000000ffff0ff0 DR7: 0000000000000600
>  Call Trace:
>   <TASK>
>   ? __die_body+0x1b/0x60
>   ? die_addr+0x43/0x70
>   ? exc_general_protection+0x121/0x210
>   ? asm_exc_general_protection+0x22/0x30
>   ? static_call_del_module+0x113/0x280
>   ? __SCT__tp_func_ipi_exit+0x8/0x8
>   static_call_module_notify+0x27f/0x390
>   ? rcu_segcblist_inc_len+0x17/0x20
>   notifier_call_chain+0xbf/0x280
>   notifier_call_chain_robust+0x7f/0xe0
>   ? notifier_call_chain+0x280/0x280
>   ? kasan_quarantine_put+0x46/0x160
>   blocking_notifier_call_chain_robust+0x5b/0x80
>   load_module+0x4d1d/0x69f0
>   ? module_frob_arch_sections+0x20/0x20
>   ? update_cfs_group+0x10c/0x2a0
>   ? __wake_up_common+0x10b/0x5d0
>   ? kernel_read_file+0x3ca/0x510
>   ? __x64_sys_fsconfig+0x650/0x650
>   ? __schedule+0xa0b/0x2a60
>   ? init_module_from_file+0xd2/0x130
>   init_module_from_file+0xd2/0x130
>   ? __ia32_sys_init_module+0xa0/0xa0
>   ? _raw_spin_lock_irqsave+0xe0/0xe0
>   ? ptrace_stop+0x487/0x790
>   idempotent_init_module+0x32d/0x6a0
>   ? init_module_from_file+0x130/0x130
>   ? __fget_light+0x57/0x500
>   __x64_sys_finit_module+0xbb/0x130
>   do_syscall_64+0x35/0x80
>   entry_SYSCALL_64_after_hwframe+0x46/0xb0
>  RIP: 0033:0x7f4ff691b839
>  Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1f f6 2c 00 f7 d8 64 89 01 48
>  RSP: 002b:00007ffc07b09718 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
>  RAX: ffffffffffffffda RBX: 000055978f13e070 RCX: 00007f4ff691b839
>  RDX: 0000000000000000 RSI: 000055978da1bc2e RDI: 0000000000000003
>  RBP: 000055978da1bc2e R08: 0000000000000000 R09: 000055978f13ddb0
>  R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
>  R13: 000055978f13e020 R14: 0000000000040000 R15: 000055978f13ddb0
>   </TASK>
>  Modules linked in: tifm_core(+)
>  Dumping ftrace buffer:
>     (ftrace buffer empty)
>  ---[ end trace 0000000000000000 ]---
>  RIP: 0010:static_call_del_module+0x113/0x280
>  Code: 3c 20 00 0f 85 ef 00 00 00 49 8b 6e 08 48 85 ed 75 0d eb 75 48 85 db 74 70 49 89 ef 48 89 dd 48 8d 7d 08 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 75 78 48 89 e8 4c 8b 6d 08 48 c1 e8 03 42 80 3c 20
>  RSP: 0018:ffff888101d3f860 EFLAGS: 00010206
>  RAX: 0b800559c89f94a0 RBX: 5c002ace44fca4f8 RCX: ffffffffa0210f00
>  RDX: ffffffffa0210ed4 RSI: ffffffffa0210edc RDI: 5c002ace44fca500
>  RBP: 5c002ace44fca4f8 R08: 0000000000000000 R09: ffffed10233e4eea
>  R10: ffffed10233e4ee9 R11: ffff888119f2774b R12: dffffc0000000000
>  R13: 80002ace3cfca4f8 R14: ffffffff85196de0 R15: ffffffff84ee9f99
>  FS:  00007f4ff6faa540(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 00007ffc3d1f19e8 CR3: 0000000109fa6001 CR4: 0000000000170ee0
>  DR0: ffffffff8faefce8 DR1: ffffffff8faefce9 DR2: ffffffff8faefcea
>  DR3: ffffffff8faefceb DR6: 00000000ffff0ff0 DR7: 0000000000000600
>  Kernel panic - not syncing: Fatal exception
>  Dumping ftrace buffer:
>     (ftrace buffer empty)
>  Kernel Offset: disabled
>  Rebooting in 1 seconds..
> 
> Fixes: 8fd4ddda2f49 ("static_call: Don't make __static_call_return0 static")
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  kernel/static_call_inline.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/static_call_inline.c b/kernel/static_call_inline.c
> index 639397b5491c..e7aa70d33530 100644
> --- a/kernel/static_call_inline.c
> +++ b/kernel/static_call_inline.c
> @@ -256,8 +256,10 @@ static int __static_call_init(struct module *mod,
>  			}
>  
>  			site_mod = kzalloc(sizeof(*site_mod), GFP_KERNEL);
> -			if (!site_mod)
> +			if (!site_mod) {
> +				key->mods = NULL;
>  				return -ENOMEM;
> +			}
>  
>  			/*
>  			 * When the key has a direct sites pointer, extract
> @@ -422,7 +424,7 @@ static void static_call_del_module(struct module *mod)
>  			;
>  
>  		if (!site_mod)
> -			continue;
> +			break;
>  
>  		*prev = site_mod->next;
>  		kfree(site_mod);