High [CVE-2026-74493] fix socket use-after-free during link group termination
This high-severity Red Hat Linux advisory covers CVE-2026-74493 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix socket use-after-free during link group termination __smc_lgr_terminate() drops conns_lock after finding a connection in lgr->conns_all, but before taking a reference on its socket.
The connection is embedded in the socket, and its registration reference protects it only while the connection remains in the tree. A concurrent close can unregister the connection and drop that reference, freeing the socket before the termination worker reaches sock_hold().
The race is reachable when close overlaps link group termination.
Local stress testing reproduced the use-after-free and KASAN reported: BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc] Write of size 4 by task kworker/3:3 Workqueue: events smc_lgr_terminate_work [smc] __smc_lgr_terminate.part.0 [smc] The socket was allocated by smc_create(), freed through slab_free_after_rcu_debug(), and was followed by: refcount_t: addition on 0; use-after-free. __smc_lgr_terminate.part.0 [smc] Take the socket reference while conns_lock still protects the tree entry.
The unregister path then cannot drop the last reference until termination has finished using the socket. This race condition can lead to a system crash, resulting in a denial of service.
Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
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