Advisory [CVE-2026-63796] reject oversized group bitmap descriptors
This security Red Hat Linux advisory covers CVE-2026-63796.
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Summary
In the Linux kernel, the following vulnerability has been resolved: ocfs2: reject oversized group bitmap descriptors ocfs2_validate_gd_parent() only bounds bg_bits against the parent allocator's chain geometry.
A malicious descriptor can still claim a bg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in the group descriptor block, so later bitmap scans and bit updates can run past bg_bitmap.
Add a physical-cap check based on ocfs2_group_bitmap_size() for the parent allocator type and reject descriptors whose bg_size or bg_bits exceed that capacity. Keep the existing chain geometry check so both the on-disk bitmap layout and the allocator metadata must agree before the descriptor is used.
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 7 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 7 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 7 days ago·verify at source
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