Medium [CVE-2026-72105] fix a bitset_size overflow on 32bit machines
This medium-severity Red Hat Linux advisory covers CVE-2026-72105 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
In the Linux kernel, the following vulnerability has been resolved: dm-log: fix a bitset_size overflow on 32bit machines Commit c20e36b7631d ("dm log: fix out-of-bounds write due to region_count overflow") made sure that region_count could fit in an unsigned int. But the bitmap memory isn't allocated based on region_count.
It uses bitset_size (a size_t variable). The first step of calculating bitset_size is to set it to region_count, rounded up to a multiple of BITS_PER_LONG.
If region_size is less than BITS_PER_LONG smaller than UINT_MAX, it will get rounded up to 2^32. On a 32bit architecture, this will make bitset_size wrap around to 0 and fail, despite region_count being valid.
Since bitset_size gets divided by 8, it can hold any valid region_count. It just needs a special case to handle the rollover.
If it is 0, the value rolled over, and bitset size should be set to the number of bytes needed to hold 2^32 bits. A flaw was found in the Linux kernel's device mapper logging (dm-log) component.
On 32-bit systems, an error in calculating the `bitset_size` can cause this variable to wrap around to zero. This incorrect calculation leads to a failure in memory allocation, which can result in a Denial of Service (DoS) condition.
Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-190.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 25 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 25 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 25 days ago·verify at source
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