Bug 2532233 (CVE-2026-89748)

Summary: CVE-2026-89748 kernel: tracing: Fix retry exhaustion in simple ring buffer reader swap
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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 tracing subsystem. An issue in the `simple_ring_buffer_swap_reader_page()` function, related to retry exhaustion during ring buffer reader page swaps, can lead to incorrect handling of successful or failed operations. This can result in corruption of the ring buffer, potentially causing system instability or denial of service.
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Description OSIDB Bzimport 2026-09-11 21:34:27 UTC 
In the Linux kernel, the following vulnerability has been resolved:

tracing: Fix retry exhaustion in simple ring buffer reader swap

simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
post-decrements it only after a failed link replacement. On the final
attempt, a successful replacement leaves retry at zero, while a failed
replacement leaves it at -1.

The current !retry test reverses both outcomes. It returns an error after
a successful final replacement, leaving the link update complete but the
reader bookkeeping unfinished. After a failed final replacement, it
falls through and updates the head and reader pointers as though the
replacement succeeded, which can corrupt the ring.

Treat only a negative counter as exhaustion and return the documented
-EBUSY error.
Comment 1 Keith Grant 2026-09-21 16:47:04 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89748.mbox