vc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98840
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-18 16:17:38 UTC
Updated2026-10-21 13:21:49 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: vc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF The reload of 'vc' added by commit 8fb9ea65c9d1 ("vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF") sits after the 'if (ret)' block, so the copy-failure break path exits the loop without reloading vc. If the vc was kfree()'d via vc_port_destruct during the unlocked copy_from_user() window, the post-loop 'if (written && vc) vcs_scr_updated(vc)' is reached with a stale non-NULL vc. The '&& vc' guard from commit a287620312dc ("vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write") only handles the NULL case, not this stale-non-NULL case; vcs_notifier() then reads param->vc->vc_num from freed memory: BUG: KASAN: slab-use-after-free in vcs_notifier+0x7c/0xd0 Read of size 2 at addr ffff888007149190 Call Trace: vcs_notifier+0x7c/0xd0 atomic_notifier_call_chain+0x70/0xa0 vcs_scr_updated+0x77/0xa0 vcs_write+0x71b/0x7e0 Allocated by task: vc_allocate -> con_install -> tty_open Freed by task: kfree <- vt_ioctl (VT_DISALLOCATE -> vc_port_destruct) Move the reload to immediately after console_lock(), before 'if (ret)', so every break path below passes a fresh vc to the post-loop vcs_scr_updated().

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 8232fca738011ca2ec865b46ec721d1796dc0580 c073d01f6f5367c3a4f07efd507274ed0d03acd0 git Not specified
CNA Linux Linux affected 73049768ad57145acd337102c5aa3c788e6642c8 1485a3dd97ab1af2605243cabe6b604546d46dd1 git Not specified
CNA Linux Linux affected 7cc3dd79777f6ae4625ec37e84dd18a26dc88bde 233a2e190b12884d186027d0b86d43a48799b69c git Not specified
CNA Linux Linux affected a287620312dc6dcb9a093417a0e589bf30fcf38a 9dfcadc5e003fb250dd471db90144bd5366140e9 git Not specified
CNA Linux Linux affected a287620312dc6dcb9a093417a0e589bf30fcf38a 226bd5603371cd9f6642cbb9e9a677f445de3530 git Not specified
CNA Linux Linux affected 43a6281790273c1b0a9ab76609ff0245b968f1e6 git Not specified
CNA Linux Linux affected b6bbb85cf45bf0b070e741997fe0af3a772c5ad5 git Not specified
CNA Linux Linux affected ff4806202749a51938236214adc0281481a57366 git Not specified
CNA Linux Linux affected 74be188eb2dc1c99d63986167b9a67d415fe7326 git Not specified
CNA Linux Linux affected 09a43e81279b8da15526da09877134b8bcf618b0 git Not specified
CNA Linux Linux affected 6.6.144 6.6.160 semver Not specified
CNA Linux Linux affected 6.12.95 6.12.113 semver Not specified
CNA Linux Linux affected 6.18.37 6.18.56 semver Not specified
CNA Linux Linux affected 5.10.260 5.11 semver Not specified
CNA Linux Linux affected 5.15.211 5.16 semver Not specified
CNA Linux Linux affected 6.1.177 6.2 semver Not specified
CNA Linux Linux affected 7.0.14 7.1 semver Not specified
CNA Linux Linux affected 7.1.2 7.2 semver Not specified
CNA Linux Linux affected 7.2 Not specified
CNA Linux Linux unaffected 7.2 semver Not specified
CNA Linux Linux unaffected 6.6.160 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.113 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.56 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.10 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/1485a3dd97ab1af2605243cabe6b604546d46dd1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/226bd5603371cd9f6642cbb9e9a677f445de3530 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9dfcadc5e003fb250dd471db90144bd5366140e9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/233a2e190b12884d186027d0b86d43a48799b69c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c073d01f6f5367c3a4f07efd507274ed0d03acd0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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