CVE-2026-53043

Description

In the Linux kernel, the following vulnerability has been resolved: ocfs2/dlm: validate qr_numregions in dlm_match_regions() Patch series "ocfs2/dlm: fix two bugs in dlm_match_regions()". In dlm_match_regions(), the qr_numregions field from a DLM_QUERY_REGION network message is used to drive loops over the qr_regions buffer without sufficient validation. This series fixes two issues: - Patch 1 adds a bounds check to reject messages where qr_numregions exceeds O2NM_MAX_REGIONS. The o2net layer only validates message byte length; it does not constrain field values, so a crafted message can set qr_numregions up to 255 and trigger out-of-bounds reads past the 1024-byte qr_regions buffer. - Patch 2 fixes an off-by-one in the local-vs-remote comparison loop, which uses '<=' instead of '<', reading one entry past the valid range even when qr_numregions is within bounds. This patch (of 2): The qr_numregions field from a DLM_QUERY_REGION network message is used directly as loop bounds in dlm_match_regions() without checking against O2NM_MAX_REGIONS. Since qr_regions is sized for at most O2NM_MAX_REGIONS (32) entries, a crafted message with qr_numregions > 32 causes out-of-bounds reads past the qr_regions buffer. Add a bounds check for qr_numregions before entering the loops.

References

• https://git.kernel.org/stable/c/1f8b91275912cd428289c1fb424bebd7ff5302bd
• https://git.kernel.org/stable/c/3c2d0de23ae4be22b6c18e8f0915be74d3b5fb21
• https://git.kernel.org/stable/c/3f474c33ebc2e2ca3fcb587d7de4375348f13373
• https://git.kernel.org/stable/c/6c6e8fc3c007319981647b410c29bb5775048551
• https://git.kernel.org/stable/c/7ab3fbb01bc6d79091bc375e5235d360cd9b78be