linux-kernel - Re: [PATCH net] net/smc: fix general protection fault in __smc_diag

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Message-ID: <CANn89iLOyFnwD+monMHCmTgfZEAPWmhrZu-=8mvtMGyM9FG49g@mail.gmail.com>
Date: Thu, 25 Sep 2025 07:32:27 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: Wang Liang <wangliang74@...wei.com>, Kuniyuki Iwashima <kuniyu@...gle.com>
Cc: alibuda@...ux.alibaba.com, dust.li@...ux.alibaba.com, 
	sidraya@...ux.ibm.com, wenjia@...ux.ibm.com, mjambigi@...ux.ibm.com, 
	tonylu@...ux.alibaba.com, guwen@...ux.alibaba.com, davem@...emloft.net, 
	kuba@...nel.org, pabeni@...hat.com, horms@...nel.org, yuehaibing@...wei.com, 
	zhangchangzhong@...wei.com, linux-kernel@...r.kernel.org, 
	netdev@...r.kernel.org, linux-rdma@...r.kernel.org, 
	linux-s390@...r.kernel.org
Subject: Re: [PATCH net] net/smc: fix general protection fault in __smc_diag_dump

On Mon, Sep 22, 2025 at 4:57 AM Wang Liang <wangliang74@...wei.com> wrote:
>
> The syzbot report a crash:
>
>   Oops: general protection fault, probably for non-canonical address 0xfbd5a5d5a0000003: 0000 [#1] SMP KASAN NOPTI
>   KASAN: maybe wild-memory-access in range [0xdead4ead00000018-0xdead4ead0000001f]
>   CPU: 1 UID: 0 PID: 6949 Comm: syz.0.335 Not tainted syzkaller #0 PREEMPT(full)
>   Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
>   RIP: 0010:smc_diag_msg_common_fill net/smc/smc_diag.c:44 [inline]
>   RIP: 0010:__smc_diag_dump.constprop.0+0x3ca/0x2550 net/smc/smc_diag.c:89
>   Call Trace:
>    <TASK>
>    smc_diag_dump_proto+0x26d/0x420 net/smc/smc_diag.c:217
>    smc_diag_dump+0x27/0x90 net/smc/smc_diag.c:234
>    netlink_dump+0x539/0xd30 net/netlink/af_netlink.c:2327
>    __netlink_dump_start+0x6d6/0x990 net/netlink/af_netlink.c:2442
>    netlink_dump_start include/linux/netlink.h:341 [inline]
>    smc_diag_handler_dump+0x1f9/0x240 net/smc/smc_diag.c:251
>    __sock_diag_cmd net/core/sock_diag.c:249 [inline]
>    sock_diag_rcv_msg+0x438/0x790 net/core/sock_diag.c:285
>    netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
>    netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
>    netlink_unicast+0x5a7/0x870 net/netlink/af_netlink.c:1346
>    netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896
>    sock_sendmsg_nosec net/socket.c:714 [inline]
>    __sock_sendmsg net/socket.c:729 [inline]
>    ____sys_sendmsg+0xa95/0xc70 net/socket.c:2614
>    ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668
>    __sys_sendmsg+0x16d/0x220 net/socket.c:2700
>    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>    do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
>    entry_SYSCALL_64_after_hwframe+0x77/0x7f
>    </TASK>
>
> The process like this:
>
>                (CPU1)              |             (CPU2)
>   ---------------------------------|-------------------------------
>   inet_create()                    |
>     // init clcsock to NULL        |
>     sk = sk_alloc()                |
>                                    |
>     // unexpectedly change clcsock |
>     inet_init_csk_locks()          |
>                                    |
>     // add sk to hash table        |
>     smc_inet_init_sock()           |
>       smc_sk_init()                |
>         smc_hash_sk()              |
>                                    | // traverse the hash table
>                                    | smc_diag_dump_proto
>                                    |   __smc_diag_dump()
>                                    |     // visit wrong clcsock
>                                    |     smc_diag_msg_common_fill()
>     // alloc clcsock               |
>     smc_create_clcsk               |
>       sock_create_kern             |
>
> With CONFIG_DEBUG_LOCK_ALLOC=y, the smc->clcsock is unexpectedly changed
> in inet_init_csk_locks(), because the struct smc_sock does not have struct
> inet_connection_sock as the first member.
>
> Previous commit 60ada4fe644e ("smc: Fix various oops due to inet_sock type
> confusion.") add inet_sock as the first member of smc_sock. For protocol
> with INET_PROTOSW_ICSK, use inet_connection_sock instead of inet_sock is
> more appropriate.
>
> Reported-by: syzbot+f775be4458668f7d220e@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=f775be4458668f7d220e
> Tested-by: syzbot+f775be4458668f7d220e@...kaller.appspotmail.com
> Fixes: d25a92ccae6b ("net/smc: Introduce IPPROTO_SMC")
> Signed-off-by: Wang Liang <wangliang74@...wei.com>
> ---
>  net/smc/smc.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/smc/smc.h b/net/smc/smc.h
> index 2c9084963739..1b20f0c927d3 100644
> --- a/net/smc/smc.h
> +++ b/net/smc/smc.h
> @@ -285,7 +285,7 @@ struct smc_connection {
>  struct smc_sock {                              /* smc sock container */
>         union {
>                 struct sock             sk;
> -               struct inet_sock        icsk_inet;
> +               struct inet_connection_sock     inet_conn;
>         };
>         struct socket           *clcsock;       /* internal tcp socket */
>         void                    (*clcsk_state_change)(struct sock *sk);
> --
> 2.34.1
>

Kuniyuki, can you please review, I think you had a related fix recently.

Thanks.

commit 60ada4fe644edaa6c2da97364184b0425e8aeaf5
Author: Kuniyuki Iwashima <kuniyu@...gle.com>
Date:   Fri Jul 11 06:07:52 2025 +0000

    smc: Fix various oops due to inet_sock type confusion.