CVE-2026-90162ksmbd: defer publishing granted locks to prevent UAF/double-free race

Official 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 packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/f1371a140722c1d6868f9acf69d601de7d4142bf
• https://git.kernel.org/stable/c/b68d4bb6b03a667c305626bd2c242fd162bac17e
• https://git.kernel.org/stable/c/65f54ed0289e9a57e6c60b14347ccea4c318f1fc
• https://git.kernel.org/stable/c/ff6870cf3b7eccc69d03cbb6f23e3995d96e9a8d
• https://git.kernel.org/stable/c/a1d26dfb32919088e3638dca01068df3c4507433
• https://git.kernel.org/stable/c/29f74f0f2e6df3b393b7b66e810136d0c64e3c59