CVE-2023-53323: 
Linux Kernel vulnerability analysis and mitigation

A vulnerability has been identified in the Linux kernel's ext2/dax functionality, tracked as CVE-2023-53323. The issue occurs when handling page-aligned lengths in ext2setsize, specifically when the PAGEALIGN(x) macro processes a value that is already page-aligned. This vulnerability was disclosed and documented in September 2025 (NVD).

The vulnerability stems from the PAGEALIGN(x) macro behavior when handling page-aligned values. When x is already page-aligned, the macro returns x unchanged. In the context of daxzerorange() function, if x is 0, this leads to a length of 0 being passed to ->iomapbegin(). In ext2, this triggers a BUGON(maxblocks == 0) condition in ext2getblocks. The correct handling should involve calling daxtruncate_page() which properly manages cases where the offset is not page/block aligned (NVD).

When exploited, this vulnerability causes a kernel BUG condition, leading to system instability. The issue can be triggered on fsdax mounted pmem devices through simple file operations, potentially affecting system reliability and availability (NVD).

The vulnerability has been resolved in the Linux kernel through a fix that properly handles page-aligned lengths in ext2setsize. The fix involves implementing correct checks for page alignment and ensuring proper calling of daxtruncate_page() when necessary (NVD).