CVE-2026-74692 is a vulnerability in Linux Kernel
Published on August 22, 2026
net/smc: fix TOCTOU race between smc_listen_out() and listener close
In the Linux kernel, the following vulnerability has been resolved:
net/smc: fix TOCTOU race between smc_listen_out() and listener close
smc_listen_out() reads lsmc->sk.sk_state without the listener lock,
then acquires lock_sock_nested() only after the check passes. This
opens a window where smc_close_active() can transition the listener
to SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept
queue, and release the lock, all between the lockless read and the
delayed lock acquisition:
smc_listen_work (smc_hs_wq) smc_close_active()
------------------------------- -------------------------
release_sock(child)
if (sk_state == SMC_LISTEN) TRUE
lock_sock(listener)
sk_state = SMC_CLOSED
smc_close_cleanup_listen()
release_sock(listener)
flush_work(tcp_listen_work)
lock_sock_nested(listener)
smc_accept_enqueue(listener, child) /* child enqueued on dead listener */
smc_close_active() flushes only tcp_listen_work. Work items already
dispatched onto smc_hs_wq for the CLC handshake continue running
unguarded. smc_accept_enqueue() takes a sock_hold() on the child that
is never released, so the child smc_sock, its clcsock, and the
reference all leak. A remote peer that opens TCP connections while the
server calls close() can exhaust kernel memory.
Move lock_sock_nested() to before the sk_state check so that the test
and the enqueue are atomic under the listener lock.
Products Associated with CVE-2026-74692
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Affected Versions
Linux:- Version fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and below 53c7938d8bcfde3296ec1a347ba2a9393c1fdcfa is affected.
- Version fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and below feb71634bb1abab3e8fb5cde874b27001cc1282e is affected.
- Version fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and below 01865e1ddb126b25ac9eba5cdd7ec49e11183a64 is affected.
- Version fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and below 00f89433777236ced4771211047fb5d4cd581cea is affected.
- Version fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and below 78e5ebcd1c10ed7c8bda0a99e0abd5b62da86d67 is affected.
- Version fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and below ff5bcd804b5bc5c64736b7d318c20e12ea9506b8 is affected.
- Version fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9 and below 185a4caeecabc150106deda1da170b09f2ad803f is affected.
- Version d1d004585b40c212b338fc8a40cbaaf230ea4703 is affected.
- Version 4.19.299 and below 4.20 is affected.
- Version 5.1 is affected.
- Before 5.1 is unaffected.
- Version 5.15.216, <= 5.15.* is unaffected.
- Version 6.1.183, <= 6.1.* is unaffected.
- Version 6.6.152, <= 6.6.* is unaffected.
- Version 6.12.104, <= 6.12.* is unaffected.
- Version 6.18.45, <= 6.18.* is unaffected.
- Version 7.1.9, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.