PT-2026-61090 · Linux · Linux
CVE-2026-53385
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Published
2026-07-19
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Updated
2026-07-19
None
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In the Linux kernel, the following vulnerability has been resolved:
vc screen: fix null-ptr-deref in vcs notifier() during concurrent vcs write
A KASAN null-ptr-deref was observed in vcs notifier():
BUG: KASAN: null-ptr-deref in vcs notifier+0x98/0x130
Read of size 2 at addr qmp cmd name: qmp capabilities, arguments: {}
The issue is a race condition in vcs write(). When the console lock is
temporarily dropped (to copy data from userspace), the vc data pointer
obtained from vcs vc() may become stale. After re-acquiring the lock,
vcs vc() is called again to re-validate the pointer. If the vc has been
deallocated in the meantime, vcs vc() returns NULL, and the while loop
breaks (with written > 0). However, after the loop, vcs scr updated(vc)
is still called with the now-NULL vc pointer, leading to a null pointer
dereference in the notifier chain (vcs notifier dereferences param->vc).
Fix this by adding a NULL check for vc before calling vcs scr updated().
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Related Identifiers
Affected Products
Linux