Bug 2424989 (CVE-2023-54021)

Summary: CVE-2023-54021 kernel: ext4: set goal start correctly in ext4_mb_normalize_request
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-12-24 12:06:16 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ext4: set goal start correctly in ext4_mb_normalize_request

We need to set ac_g_ex to notify the goal start used in
ext4_mb_find_by_goal. Set ac_g_ex instead of ac_f_ex in
ext4_mb_normalize_request.
Besides we should assure goal start is in range [first_data_block,
blocks_count) as ext4_mb_initialize_context does.

[ Added a check to make sure size is less than ar->pright; otherwise
  we could end up passing an underflowed value of ar->pright - size to
  ext4_get_group_no_and_offset(), which will trigger a BUG_ON later on.
  - TYT ]
Comment 1 Alexander B 2025-12-25 10:38:43 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025122433-CVE-2023-54021-15bf@gregkh/T