Bug 2536629 (CVE-2026-90107)

Summary: CVE-2026-90107 kernel: net/smc: free pending qentry in smc_llc_flow_stop() before memset
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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Doc Text:
A flaw was found in the Linux kernel's net/smc component. The `smc_llc_flow_stop()` function, responsible for stopping a flow, performs a blind memory reset without first freeing a pending queue entry. This can lead to a memory leak if a duplicate link message arrives during a specific timing window, causing the `flow->qentry` to be overwritten without being deallocated. This vulnerability results in the leakage of kernel memory.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-17 18:56:57 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net/smc: free pending qentry in smc_llc_flow_stop() before memset

smc_llc_flow_stop() resets a flow struct with a blind memset:

	spin_lock_bh(&lgr->llc_flow_lock);
	memset(flow, 0, sizeof(*flow));
	flow->type = SMC_LLC_FLOW_NONE;
	spin_unlock_bh(&lgr->llc_flow_lock);

If flow->qentry is non-NULL at this point the pointer is overwritten without the
allocation being freed, leaking one kmalloc object.

A late-arriving duplicate CONFIRM_LINK or ADD_LINK_CONT message can set
flow->qentry after the legitimate message has been consumed by the waiter via
smc_llc_flow_qentry_clr() (which NULLs the pointer but leaves flow->type
non-zero) but before the flow completes and smc_llc_flow_stop() runs.  In that
window the duplicate is stashed into flow->qentry, and then lost when
smc_llc_flow_stop() zeros the struct.

Call smc_llc_flow_qentry_del() inside the lock before the memset.
smc_llc_flow_qentry_del() already checks flow->qentry before freeing, so the
normal case where no entry is pending is a no-op.
Comment 1 Keith Grant 2026-09-22 22:21:25 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90107.mbox