CVE-2026-43359

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