Описание
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().
A flaw was found in the Linux kernel's Squashfs filesystem. A local attacker can exploit this vulnerability by simultaneously mounting a Squashfs filesystem and issuing a specific input/output control (ioctl) command. This can lead to an incorrect block size calculation, causing a shift-out-of-bounds error. This memory corruption vulnerability can result in a denial of service or potentially lead to more severe system compromise.
Отчет
This moderate impact flaw in the Linux kernel's Squashfs filesystem is present in Red Hat Enterprise Linux 7, 8, 9, and 10, which allows a local attacker to cause a denial of service or a potential system compromise by simultaneously mounting a Squashfs filesystem and issuing a specific ioctl command, leading to an incorrect block size calculation and a shift-out-of-bounds read issue due to an incorrect function return problem.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 10 | kernel | Fixed | RHSA-2026:2282 | 09.02.2026 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | kernel | Fixed | RHSA-2026:3579 | 03.03.2026 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | kernel-rt | Fixed | RHSA-2026:3634 | 03.03.2026 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | kernel | Fixed | RHSA-2026:3685 | 03.03.2026 |
| Red Hat Enterprise Linux 8 | kernel-rt | Fixed | RHSA-2026:1661 | 02.02.2026 |
| Red Hat Enterprise Linux 8 | kernel | Fixed | RHSA-2026:1662 | 02.02.2026 |
| Red Hat Enterprise Linux 8.2 Advanced Update Support | kernel | Fixed | RHSA-2026:3388 | 26.02.2026 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | kernel | Fixed | RHSA-2026:3360 | 25.02.2026 |
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Дополнительная информация
Статус:
EPSS
7.1 High
CVSS3
Связанные уязвимости
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 l...
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
In the Linux kernel, the following vulnerability has been resolved: S ...
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 'unsign...
EPSS
7.1 High
CVSS3