Bug 2536437 (CVE-2026-90057)

Summary: CVE-2026-90057 kernel: slip: remove slip_hangup() to fix use-after-free in slip_receive_buf()
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 Serial Line Internet Protocol (SLIP) implementation. A local attacker could exploit a race condition during a tty hangup operation, causing the `slip_receive_buf()` function to access memory after it has been freed. This use-after-free vulnerability can lead to information disclosure or system instability.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Embargoed:

Description OSIDB Bzimport 2026-09-17 17:50:32 UTC 
In the Linux kernel, the following vulnerability has been resolved:

slip: remove slip_hangup() to fix use-after-free in slip_receive_buf()

Jaeyoung Chung and Eulgyu Kim reported a slab-use-after-free read
in slip_receive_buf() when racing against tty hangup.

tty_ldisc_hangup() calls ld->ops->hangup() while holding only
a read lock on tty->ldisc_sem (via tty_ldisc_ref()).
Because slip_hangup() simply called slip_close(), it ran concurrently
with reader functions such as slip_receive_buf().

slip_close() unregisters and frees the net device and its private
struct slip, causing concurrent reader threads in slip_receive_buf()
to dereference freed memory.

Line discipline close() is already guaranteed to be called under
the write lock of tty->ldisc_sem during hangup processing
(in tty_ldisc_reinit() or tty_ldisc_kill()).

Remove slip_hangup() so teardown is serialized cleanly by slip_close().
Comment 1 Keith Grant 2026-09-22 15:16:21 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90057.mbox