CVE-2026-43359

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix transaction abort on set received ioctl due to item overflow If the set received ioctl fails due to an item overflow when attempting to add the BTRFS_UUID_KEY_RECEIVED_SUBVOL we have to abort the transaction since we did some metadata updates before. This means that if a user calls this ioctl with the same received UUID field for a lot of subvolumes, we will hit the overflow, trigger the transaction abort and turn the filesystem into RO mode. A malicious user could exploit this, and this ioctl does not even requires that a user has admin privileges (CAP_SYS_ADMIN), only that he/she owns the subvolume. Fix this by doing an early check for item overflow before starting a transaction. This is also race safe because we are holding the subvol_sem semaphore in exclusive (write) mode. A test case for fstests will follow soon.

References

• https://git.kernel.org/stable/c/2e57b8cac2ba0d38aac76c1ecdfd8b899e3581a5
• https://git.kernel.org/stable/c/41fb97353ff58fa4f31904c343fc8e3df2f7517d
• https://git.kernel.org/stable/c/87f2c46003fce4d739138aab4af1942b1afdadac
• https://git.kernel.org/stable/c/b19c0465e4daad5aa8f60552ea0578cf31a11b1e
• https://git.kernel.org/stable/c/b9914db13ac15aca3b74544c0bb1a2e0dad1f174