CVE-2025-37858

In the Linux kernel, the following vulnerability has been resolved: fs/jfs: Prevent integer overflow in AG size calculation The JFS filesystem calculates allocation group (AG) size using 1 <<
l2agsize in dbExtendFS(). When l2agsize exceeds 31 (possible with >2TB
aggregates on 32-bit systems), this 32-bit shift operation causes undefined
behavior and improper AG sizing. On 32-bit architectures:
- Left-shifting 1 by 32+ bits results in 0 due to integer overflow
- This creates invalid AG sizes (0 or garbage values) in
sbi->bmap->db_agsize
- Subsequent block allocations would reference invalid AG structures
- Could lead to: - Filesystem corruption during extend operations - Kernel crashes due to invalid memory accesses - Security vulnerabilities via malformed on-disk structures Fix by casting to s64 before shifting:
bmp->db_agsize = (s64)1 << l2agsize; This ensures 64-bit arithmetic even on 32-bit architectures. The cast
matches the data type of db_agsize (s64) and follows similar patterns in
JFS block calculation code. Found by Linux Verification Center (linuxtesting.org) with SVACE.