CVE-2025-38415

Summary

In the Linux kernel, the following vulnerability has been resolved:

Squashfs: check return result of sb_min_blocksize

Syzkaller reports an "UBSAN: shift-out-of-bounds in squashfs_bio_read" bug.

Syzkaller forks multiple processes which after mounting the Squashfs filesystem, issues an ioctl("/dev/loop0", LOOP_SET_BLOCK_SIZE, 0x8000). Now if this ioctl occurs at the same time another process is in the process of mounting a Squashfs filesystem on /dev/loop0, the failure occurs. When this happens the following code in squashfs_fill_super() fails.

msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); msblk->devblksize_log2 = ffz(~msblk->devblksize);

sb_min_blocksize() returns 0, which means msblk->devblksize is set to 0.

As a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2 is set to 64.

This subsequently causes the

UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long')

This commit adds a check for a 0 return by sb_min_blocksize().

Affected Software

VendorProductVersion RangeStatus
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac < db7096ea160e40d78c67fce52e7cc51bde049497affected
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac < 549f9e3d7b60d53808c98b9fde49b4f46d0524a5affected
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac < 5c51aa862cbeed2f3887f0382a2708956710bd68affected
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac < 6abf6b78c6fb112eee495f5636ffcc350dd2ce25affected
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac < 4f99357dadbf9c979ad737156ad4c37fadf7c56baffected
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac < 0aff95d9bc7fb5400ca8af507429c4b067bdb425affected
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac < 295ab18c2dbce8d0ac6ecf7c5187e16e1ac8b282affected
LinuxLinux0aa666190509ffab81c202c5095a166be23961ac < 734aa85390ea693bb7eaf2240623d41b03705c84affected
LinuxLinux2.6.29affected
LinuxLinux0 < 2.6.29unaffected
LinuxLinux5.4.295 <= 5.4.*unaffected
LinuxLinux5.10.239 <= 5.10.*unaffected
LinuxLinux5.15.186 <= 5.15.*unaffected
LinuxLinux6.1.142 <= 6.1.*unaffected
LinuxLinux6.6.94 <= 6.6.*unaffected
LinuxLinux6.12.34 <= 6.12.*unaffected
LinuxLinux6.15.3 <= 6.15.*unaffected
LinuxLinux6.16 <= *unaffected

Weaknesses

ADP Enrichment

CVE Program Container

Additional References

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References