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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-98840

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

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In 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().

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 43a6281790273c1b0a9ab76609ff0245b968f1e6 to < cbc05413d3694193494b2374b56bae801ac41fecaffected
  • b6bbb85cf45bf0b070e741997fe0af3a772c5ad5 to < 942742000a0288d4ca60c448894aabacd48004d5affected
  • ff4806202749a51938236214adc0281481a57366 to < c9f56d4b29792a62b17f2051ba93fd3b40a479ecaffected
  • 8232fca738011ca2ec865b46ec721d1796dc0580 to < c073d01f6f5367c3a4f07efd507274ed0d03acd0affected
  • 73049768ad57145acd337102c5aa3c788e6642c8 to < 1485a3dd97ab1af2605243cabe6b604546d46dd1affected
  • 7cc3dd79777f6ae4625ec37e84dd18a26dc88bde to < 233a2e190b12884d186027d0b86d43a48799b69caffected
  • a287620312dc6dcb9a093417a0e589bf30fcf38a to < 9dfcadc5e003fb250dd471db90144bd5366140e9affected
  • a287620312dc6dcb9a093417a0e589bf30fcf38a to < 226bd5603371cd9f6642cbb9e9a677f445de3530affected
  • 74be188eb2dc1c99d63986167b9a67d415fe7326affected
  • 09a43e81279b8da15526da09877134b8bcf618b0affected
  • 5.10.260 to < 5.10.273affected
  • 5.15.211 to < 5.15.224affected
  • 6.1.177 to < 6.1.191affected
  • 6.6.144 to < 6.6.160affected
  • 6.12.95 to < 6.12.113affected
  • 6.18.37 to < 6.18.56affected
  • 7.0.14 to < 7.1affected
  • 7.1.2 to < 7.2affected

Linux Linux

Default version status: affected

  • 7.2affected
  • 0 to < 7.2unaffected
  • 5.10.273 to ≤ 5.10.*unaffected
  • 5.15.224 to ≤ 5.15.*unaffected
  • 6.1.191 to ≤ 6.1.*unaffected
  • 6.6.160 to ≤ 6.6.*unaffected
  • 6.12.113 to ≤ 6.12.*unaffected
  • 6.18.56 to ≤ 6.18.*unaffected
  • 7.2.10 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References