CVE-2025-40357
Unknown Unknown - Not Provided
General Protection Fault in Linux Kernel net/smc Component

Publication date: 2025-12-16

Last updated on: 2025-12-16

Assigner: kernel.org

Description
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.
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Meta Information
Published
2025-12-16
Last Modified
2025-12-16
Generated
2026-05-07
AI Q&A
2025-12-16
EPSS Evaluated
2026-05-05
NVD
CVE-2025-40357
EUVD
EUVD-2025-203630
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability manifests as a general protection fault (crash) in the Linux kernel related to the net/smc module, specifically in the __smc_diag_dump function. Detection involves monitoring kernel logs for Oops messages indicating a general protection fault with references to smc_diag.c and smc_diag_dump. You can check the kernel ring buffer for such messages using the command: dmesg | grep -i 'smc_diag' or dmesg | grep -i 'general protection fault'. Additionally, monitoring for crashes or oops events related to smc_diag_dump in /var/log/kern.log or /var/log/messages can help detect this issue. There are no specific network commands provided to detect this vulnerability directly, but kernel log inspection is key.


Can you explain this vulnerability to me?

This vulnerability is a general protection fault in the Linux kernel's net/smc subsystem, specifically in the __smc_diag_dump function. It occurs due to an unexpected change of the smc->clcsock pointer in the inet_init_csk_locks() function, which leads to a crash when the system tries to access an invalid or non-canonical memory address. The issue arises because the INET_PROTOSW_ICSK flag was incorrectly used by smc, causing improper handling of socket structures and resulting in a kernel crash.


How can this vulnerability impact me? :

This vulnerability can cause the Linux kernel to crash due to a general protection fault, leading to system instability or denial of service. Since it involves kernel memory access errors, it may disrupt normal network operations on affected systems, potentially causing downtime or requiring a reboot to recover.


What immediate steps should I take to mitigate this vulnerability?

The vulnerability is fixed by removing the INET_PROTOSW_ICSK flag from the smc implementation and reverting a previous commit that caused unsafe casting. Immediate mitigation would involve updating the Linux kernel to a version that includes this fix to prevent the general protection fault in __smc_diag_dump.


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