CVE-2025-40357

In the Linux kernel, the following vulnerability has been resolved:

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 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(). The INET_PROTOSW_ICSK flag is no need by smc,

just remove it.

After removing the INET_PROTOSW_ICSK flag, this patch alse revert

commit 6fd27ea183c2 ("net/smc: fix lacks of icsk_syn_mss with IPPROTO_SMC")

to avoid casting smc_sock to inet_connection_sock.