Bug 2466797 (CVE-2026-43066)

Summary: CVE-2026-43066 kernel: ext4: fix iloc.bh leak in ext4_fc_replay_inode() error paths
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's ext4 filesystem. Specific error handling paths within the `ext4_fc_replay_inode()` function failed to release a buffer head resource, leading to a resource leak. A local attacker could potentially exploit this vulnerability by triggering these error paths, which may result in a Denial of Service (DoS) due to resource exhaustion.
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Description OSIDB Bzimport 2026-05-05 17:03:11 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ext4: fix iloc.bh leak in ext4_fc_replay_inode() error paths

During code review, Joseph found that ext4_fc_replay_inode() calls
ext4_get_fc_inode_loc() to get the inode location, which holds a
reference to iloc.bh that must be released via brelse().

However, several error paths jump to the 'out' label without
releasing iloc.bh:

 - ext4_handle_dirty_metadata() failure
 - sync_dirty_buffer() failure
 - ext4_mark_inode_used() failure
 - ext4_iget() failure

Fix this by introducing an 'out_brelse' label placed just before
the existing 'out' label to ensure iloc.bh is always released.

Additionally, make ext4_fc_replay_inode() propagate errors
properly instead of always returning 0.
Comment 1 Alexander B 2026-05-06 09:29:22 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050532-CVE-2026-43066-4d3f@gregkh/T