netdev - Re: [PATCH net] net/smc: do not leave a dangling sk pointer in __smc

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Message-ID: <b5b668d4-a03f-449a-a0bb-0b8eb29126b3@linux.ibm.com>
Date: Thu, 7 Nov 2024 12:56:54 +0100
From: Wenjia Zhang <wenjia@...ux.ibm.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski
 <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
        netdev@...r.kernel.org, eric.dumazet@...il.com,
        Kuniyuki Iwashima <kuniyu@...zon.com>,
        Ignat Korchagin <ignat@...udflare.com>,
        "D. Wythe"
 <alibuda@...ux.alibaba.com>,
        Dust Li <dust.li@...ux.alibaba.com>
Subject: Re: [PATCH net] net/smc: do not leave a dangling sk pointer in
 __smc_create()



On 07.11.24 09:32, Eric Dumazet wrote:
> On Thu, Nov 7, 2024 at 9:28 AM Wenjia Zhang <wenjia@...ux.ibm.com> wrote:
>>
>>
>>
>> On 06.11.24 23:19, Eric Dumazet wrote:
>>> Thanks to commit 4bbd360a5084 ("socket: Print pf->create() when
>>> it does not clear sock->sk on failure."), syzbot found an issue with AF_SMC:
>>>
>>> smc_create must clear sock->sk on failure, family: 43, type: 1, protocol: 0
>>>    WARNING: CPU: 0 PID: 5827 at net/socket.c:1565 __sock_create+0x96f/0xa30 net/socket.c:1563
>>> Modules linked in:
>>> CPU: 0 UID: 0 PID: 5827 Comm: syz-executor259 Not tainted 6.12.0-rc6-next-20241106-syzkaller #0
>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
>>>    RIP: 0010:__sock_create+0x96f/0xa30 net/socket.c:1563
>>> Code: 03 00 74 08 4c 89 e7 e8 4f 3b 85 f8 49 8b 34 24 48 c7 c7 40 89 0c 8d 8b 54 24 04 8b 4c 24 0c 44 8b 44 24 08 e8 32 78 db f7 90 <0f> 0b 90 90 e9 d3 fd ff ff 89 e9 80 e1 07 fe c1 38 c1 0f 8c ee f7
>>> RSP: 0018:ffffc90003e4fda0 EFLAGS: 00010246
>>> RAX: 099c6f938c7f4700 RBX: 1ffffffff1a595fd RCX: ffff888034823c00
>>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
>>> RBP: 00000000ffffffe9 R08: ffffffff81567052 R09: 1ffff920007c9f50
>>> R10: dffffc0000000000 R11: fffff520007c9f51 R12: ffffffff8d2cafe8
>>> R13: 1ffffffff1a595fe R14: ffffffff9a789c40 R15: ffff8880764298c0
>>> FS:  000055557b518380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00007fa62ff43225 CR3: 0000000031628000 CR4: 00000000003526f0
>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>> Call Trace:
>>>    <TASK>
>>>     sock_create net/socket.c:1616 [inline]
>>>     __sys_socket_create net/socket.c:1653 [inline]
>>>     __sys_socket+0x150/0x3c0 net/socket.c:1700
>>>     __do_sys_socket net/socket.c:1714 [inline]
>>>     __se_sys_socket net/socket.c:1712 [inline]
>>>
>>> For reference, see commit 2d859aff775d ("Merge branch
>>> 'do-not-leave-dangling-sk-pointers-in-pf-create-functions'")
>>>
>>> Fixes: d25a92ccae6b ("net/smc: Introduce IPPROTO_SMC")
>>> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
>>> Cc: Kuniyuki Iwashima <kuniyu@...zon.com>
>>> Cc: Ignat Korchagin <ignat@...udflare.com>
>>> Cc: D. Wythe <alibuda@...ux.alibaba.com>
>>> Cc: Wenjia Zhang <wenjia@...ux.ibm.com>
>>> Cc: Dust Li <dust.li@...ux.alibaba.com>
>>> ---
>>
>> Thank you, Eric, for fixing it! The code looks good to me.
>> Should the fixed commit not be 2fe5273f149c instead of d25a92ccae6b?
>>
> 
> The bug was there, even before 2fe5273f149c ("net/smc: prevent UAF in
> inet_create()")
> 
> Thanks.
ok, that sounds reasonable to me.

Reviewed-by: Wenjia Zhang <wenjia@...ux.ibm.com>

Thanks,
Wenjia