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

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Message-ID: <20250922121818.654011-1-wangliang74@huawei.com>
Date: Mon, 22 Sep 2025 20:18:18 +0800
From: Wang Liang <wangliang74@...wei.com>
To: <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>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<horms@...nel.org>
CC: <yuehaibing@...wei.com>, <zhangchangzhong@...wei.com>,
	<wangliang74@...wei.com>, <linux-kernel@...r.kernel.org>,
	<netdev@...r.kernel.org>, <linux-rdma@...r.kernel.org>,
	<linux-s390@...r.kernel.org>
Subject: [PATCH net] net/smc: fix general protection fault in __smc_diag_dump

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