Описание
In the Linux kernel, the following vulnerability has been resolved:
dm log: fix out-of-bounds write due to region_count overflow
The local variable region_count in create_log_context() is declared as
unsigned int (32-bit), but dm_sector_div_up() returns sector_t (64-bit).
When a device-mapper target has a sufficiently large ti->len with a small
region_size, the division result can exceed UINT_MAX. The truncated
value is then used to calculate bitset_size, causing clean_bits,
sync_bits, and recovering_bits to be allocated far smaller than needed
for the actual number of regions.
Subsequent log operations (log_set_bit, log_clear_bit, log_test_bit) use
region indices derived from the full untruncated region space, causing
out-of-bounds writes to kernel heap memory allocated by vmalloc.
This can be reproduced by creating a mirror target whose region_count
overflows 32 bits:
dmsetup create bigzero --table '0 8589934594 zero'
dmsetup create mymirror --table '0 8589934594 mirror
core 2 2 nosync 2 /dev/mapper/bigzero 0
/dev/mapper/bigzero 0'
The status output confirms the truncation (sync_count=1 instead of
4294967297, because 0x100000001 was truncated to 1):
$ dmsetup status mymirror
0 8589934594 mirror 2 254:1 254:1 1/4294967297 ...
This leads to a kernel crash in core_in_sync:
BUG: scheduling while atomic: (udev-worker)/9150/0x00000000
RIP: 0010:core_in_sync+0x14/0x30 [dm_log]
CR2: 0000000000000008
Fixing recursive fault but reboot is needed!
Fix by widening the local region_count to sector_t and adding an
explicit overflow check before the value is assigned to lc->region_count.
A flaw was found in the Linux kernel's device-mapper log (dm log) component. A local attacker could exploit an integer overflow vulnerability where a 64-bit value is truncated to 32 bits, leading to undersized memory allocations. This allows for out-of-bounds writes to kernel memory during log operations. Successful exploitation of this flaw can cause a kernel crash, resulting in a Denial of Service (DoS) for the affected system.
Отчет
This vulnerability is rated as Moderate severity because exploitation requires administrative privileges (specifically CAP_SYS_ADMIN) to configure device-mapper tables and construct the specific target parameters needed to trigger the integer overflow. Standard Red Hat Enterprise Linux installations restrict device-mapper management to privileged administrators, preventing unprivileged local or remote users from exercising this code path. Furthermore, triggering the condition requires configuring an unusually large device-mapper target combined with an exceptionally fine log region size, which deviates significantly from typical storage provisioning practices.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Under investigation | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 10 | kernel | Fixed | RHSA-2026:45114 | 24.07.2026 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | kernel | Fixed | RHSA-2026:55445 | 17.08.2026 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | kernel-rt | Fixed | RHSA-2026:63189 | 03.09.2026 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | kernel | Fixed | RHSA-2026:61692 | 31.08.2026 |
| Red Hat Enterprise Linux 8 | kernel-rt | Fixed | RHSA-2026:45116 | 24.07.2026 |
| Red Hat Enterprise Linux 8 | kernel | Fixed | RHSA-2026:45115 | 24.07.2026 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | kernel | Fixed | RHSA-2026:47248 | 28.07.2026 |
| Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | kernel | Fixed | RHSA-2026:47248 | 28.07.2026 |
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Дополнительная информация
Статус:
EPSS
6.3 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: dm log: fix out-of-bounds write due to region_count overflow The local variable region_count in create_log_context() is declared as unsigned int (32-bit), but dm_sector_div_up() returns sector_t (64-bit). When a device-mapper target has a sufficiently large ti->len with a small region_size, the division result can exceed UINT_MAX. The truncated value is then used to calculate bitset_size, causing clean_bits, sync_bits, and recovering_bits to be allocated far smaller than needed for the actual number of regions. Subsequent log operations (log_set_bit, log_clear_bit, log_test_bit) use region indices derived from the full untruncated region space, causing out-of-bounds writes to kernel heap memory allocated by vmalloc. This can be reproduced by creating a mirror target whose region_count overflows 32 bits: dmsetup create bigzero --table '0 8589934594 zero' dmsetup create mymirror --table '0 8589934594 mirror \ core 2 2...
In the Linux kernel, the following vulnerability has been resolved: dm log: fix out-of-bounds write due to region_count overflow The local variable region_count in create_log_context() is declared as unsigned int (32-bit), but dm_sector_div_up() returns sector_t (64-bit). When a device-mapper target has a sufficiently large ti->len with a small region_size, the division result can exceed UINT_MAX. The truncated value is then used to calculate bitset_size, causing clean_bits, sync_bits, and recovering_bits to be allocated far smaller than needed for the actual number of regions. Subsequent log operations (log_set_bit, log_clear_bit, log_test_bit) use region indices derived from the full untruncated region space, causing out-of-bounds writes to kernel heap memory allocated by vmalloc. This can be reproduced by creating a mirror target whose region_count overflows 32 bits: dmsetup create bigzero --table '0 8589934594 zero' dmsetup create mymirror --table '0 8589934594 mirror \
dm log: fix out-of-bounds write due to region_count overflow
In the Linux kernel, the following vulnerability has been resolved: d ...
EPSS
6.3 Medium
CVSS3