CVE-2025-38415 Affecting kernel-source-coco package, versions <6.4.0-15061.28.coco15sp6.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (9th percentile)

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  • Snyk IDSNYK-SLES156-KERNELSOURCECOCO-12100263
  • published21 Aug 2025
  • disclosed20 Aug 2025

Introduced: 20 Aug 2025

CVE-2025-38415  (opens in a new tab)

How to fix?

Upgrade SLES:15.6 kernel-source-coco to version 6.4.0-15061.28.coco15sp6.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-source-coco package and not the kernel-source-coco package as distributed by SLES. See How to fix? for SLES:15.6 relevant fixed versions and status.

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().

CVSS Base Scores

version 3.1