Bug 2420351 (CVE-2023-53861)

Summary: CVE-2023-53861 kernel: ext4: correct grp validation in ext4_mb_good_group
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A NULL pointer dereference vulnerability was found in the ext4 filesystem in the Linux kernel. In ext4_mb_good_group(), the group corruption check accesses the grp structure memory before verifying that grp is not NULL. If grp is NULL, this leads to a kernel crash. The fix adds a NULL check before performing the corruption check.
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Description OSIDB Bzimport 2025-12-09 02:04:55 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ext4: correct grp validation in ext4_mb_good_group

Group corruption check will access memory of grp and will trigger kernel
crash if grp is NULL. So do NULL check before corruption check.
Comment 1 Alexander B 2025-12-09 18:14:43 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025120905-CVE-2023-53861-22c6@gregkh/T