Bug 2516347 (CVE-2026-72105) - CVE-2026-72105 kernel: dm-log: fix a bitset_size overflow on 32bit machines
Summary: CVE-2026-72105 kernel: dm-log: fix a bitset_size overflow on 32bit machines
Keywords:
Status: NEW
Alias: CVE-2026-72105
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-15 06:07 UTC by OSIDB Bzimport
Modified: 2026-08-17 22:04 UTC (History)
2 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-08-15 06:07:44 UTC
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.


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