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().
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2025072513-CVE-2025-38415-c634@gregkh/T
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:1661 https://access.redhat.com/errata/RHSA-2026:1661
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2026:1662 https://access.redhat.com/errata/RHSA-2026:1662
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:2212 https://access.redhat.com/errata/RHSA-2026:2212
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2026:2282 https://access.redhat.com/errata/RHSA-2026:2282
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Extended Update Support Via RHSA-2026:2766 https://access.redhat.com/errata/RHSA-2026:2766
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.6 Extended Update Support Via RHSA-2026:3088 https://access.redhat.com/errata/RHSA-2026:3088
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions Red Hat Enterprise Linux 8.6 Telecommunications Update Service Via RHSA-2026:3268 https://access.redhat.com/errata/RHSA-2026:3268
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:3267 https://access.redhat.com/errata/RHSA-2026:3267
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Red Hat Enterprise Linux 8.8 Telecommunications Update Service Via RHSA-2026:3277 https://access.redhat.com/errata/RHSA-2026:3277
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions Via RHSA-2026:3293 https://access.redhat.com/errata/RHSA-2026:3293
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2026:3358 https://access.redhat.com/errata/RHSA-2026:3358
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Via RHSA-2026:3360 https://access.redhat.com/errata/RHSA-2026:3360
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions Via RHSA-2026:3375 https://access.redhat.com/errata/RHSA-2026:3375
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.2 Advanced Update Support Via RHSA-2026:3388 https://access.redhat.com/errata/RHSA-2026:3388
This issue has been addressed in the following products: Red Hat Enterprise Linux 10.0 Extended Update Support Via RHSA-2026:3579 https://access.redhat.com/errata/RHSA-2026:3579
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Extended Lifecycle Support Via RHSA-2026:3634 https://access.redhat.com/errata/RHSA-2026:3634
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Extended Lifecycle Support Via RHSA-2026:3685 https://access.redhat.com/errata/RHSA-2026:3685