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.
References
Configurations
Configuration 1 (hide)
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Configuration 2 (hide)
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History
No history.
Information
Published : 2025-05-09 07:16
Updated : 2025-11-12 20:09
NVD link : CVE-2025-37858
Mitre link : CVE-2025-37858
CVE.ORG link : CVE-2025-37858
JSON object : View
Products Affected
debian
- debian_linux
linux
- linux_kernel
CWE
CWE-190
Integer Overflow or Wraparound