CVE-2026-53320

Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: reject zero bd_oblocknr in nilfs_ioctl_mark_blocks_dirty() nilfs_ioctl_mark_blocks_dirty() uses bd_oblocknr to detect dead blocks by comparing it with the current block number bd_blocknr. If they differ, the block is considered dead and skipped. However, bd_oblocknr should never be 0 since block 0 typically stores the primary superblock and is never a valid GC target block. A corrupted ioctl request with bd_oblocknr set to 0 causes the comparison to incorrectly match when the lookup returns -ENOENT and sets bd_blocknr to 0, bypassing the dead block check and calling nilfs_bmap_mark() on a non-existent block. This causes nilfs_btree_do_lookup() to return -ENOENT, triggering the WARN_ON(ret == -ENOENT). Fix this by rejecting ioctl requests with bd_oblocknr set to 0 at the beginning of each iteration. [ryusuke: slightly modified the commit message and comments for accuracy]

References

• https://git.kernel.org/stable/c/4525658002be3ad310b16bf8db48c8adb6a55d32
• https://git.kernel.org/stable/c/65e07964b4b2daf9a54e686cf0fa72d74a9648a8
• https://git.kernel.org/stable/c/94094e70fe292c9566502772d4d4d6d6a99204b1
• https://git.kernel.org/stable/c/9472d37799a0b9ff9b99639f35961ac2f0b3c9be
• https://git.kernel.org/stable/c/b88f905d4449b70da6bda547be546e365e44352e