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

[Jinjie Ruan <ruanjinjie@huawei.com>]

On 2024/9/2 20:06, Christophe Leroy wrote:
> Hi,
> 
> Le 02/09/2024 à 14:01, Jinjie Ruan a écrit :
>> Hi, it seems that this bug still exit.
> 
> Can you provide more details ?
> 
> In particular, what makes you think it is the exact same bug ?

I apply this patch, and the problem not occurs.

> 
> Christophe
> 
> 
>>
>> 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);
>