CVE-2026-90162

ksmbd: defer publishing granted locks to prevent UAF/double-free race

HIGH
8.8
CVSS Score
Published: September 17, 2026 at 04:06 PM UTC
Updated: October 30, 2026 at 01:20 PM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
HIGH8.8
Exploit prediction
EPSS 0.7%

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: defer publishing granted locks to prevent UAF/double-free race In smb2_lock(), mid-batch granted locks are published to connection-wide (conn->lock_list) and file-wide (fp->lock_list) lists immediately upon vfs_lock_file() success, while also remaining tracked on the stack-local rollback_list. If a subsequent element in the same SMB2_LOCK request array fails validation or execution, the thread jumps to out: and walks rollback_list to undo previously granted locks. However, because the granted lock was already published to conn->lock_list, a concurrent UNLOCK request on the same connection can find the lock object and kfree() it before the rollback loop executes. When the granting thread subsequently walks rollback_list, it dereferences and frees the already-freed ksmbd_lock structure, resulting in a Use-After-Free and Double-Free (on both ksmbd_lock and struct file_lock). Fix this by deferring the publication of granted locks to conn->lock_list and fp->lock_list until after the entire array of lock elements has been processed without error. Mid-batch grants remain tracked exclusively on the request-local rollback_list until the whole batch succeeds, eliminating the race window.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.15e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Vendor states this is fixed in 29f74f0f2e6df3b393b7b66e810136d0c64e3c59 (fixed)
Vendor states this is fixed in a1d26dfb32919088e3638dca01068df3c4507433 (fixed)
Vendor states this is fixed in 5.15 (unaffected)
Vendor states this is fixed in 6.12.114 (unaffected)
Vendor states this is fixed in 6.18.57 (unaffected)
Vendor states this is fixed in 6.6.160 (unaffected)
Vendor states this is fixed in 7.2.6 (unaffected)
Vendor states this is fixed in 7.3 (unaffected)
Vendor states this is fixed in 7.3-rc1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

CVSS

8.8HIGHLinux
Vector?

Quick Info

StatusRECEIVED

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