Bug 2532177 (CVE-2026-80979)

Summary: CVE-2026-80979 kernel: net/smc: unregister the connection before draining the rx tasklet
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Shared Memory Communications (SMC) component. During connection termination, the SMC component may fail to properly unregister a connection before draining its receive tasklet. This can lead to a use-after-free vulnerability, where a freed memory buffer is subsequently dereferenced. A local attacker could potentially exploit this to cause a system crash, resulting in a denial of service, or potentially achieve arbitrary code execution.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 21:08:05 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net/smc: unregister the connection before draining the rx tasklet

smc_conn_free() calls smc_ism_unset_conn() only while the link group is
still on its device list, and never sets conn->killed.
smc_lgr_terminate_sched() unlinks the group immediately and defers killing
its connections to a work item, so a connection freed in that window keeps
its smcd->conn[] slot with both gates in smcd_handle_irq() open, and the
device can re-arm the receive tasklet after tasklet_kill() has returned. On
the DMB-nocopy path the ghost send buffer is freed right after that drain,
so the re-armed tasklet dereferences it.

Unregister unconditionally and drain before the detach at both teardown
sites, mirroring rmb_desc, which smc_buf_unuse() releases after the drain.
Clear conn->sndbuf_desc before freeing it as well, so a reader that samples
the pointer cannot get one that is already freed.
Comment 1 Keith Grant 2026-09-14 18:44:55 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80979.mbox