Bug 2406736 (CVE-2025-40063) - CVE-2025-40063 kernel: crypto: comp - Use same definition of context alloc and free ops
Summary: CVE-2025-40063 kernel: crypto: comp - Use same definition of context alloc an...
Keywords:
Status: NEW
Alias: CVE-2025-40063
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
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Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-10-28 12:02 UTC by OSIDB Bzimport
Modified: 2025-10-31 11:19 UTC (History)
0 users

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Description OSIDB Bzimport 2025-10-28 12:02:36 UTC
In the Linux kernel, the following vulnerability has been resolved:

crypto: comp - Use same definition of context alloc and free ops

In commit 42d9f6c77479 ("crypto: acomp - Move scomp stream allocation
code into acomp"), the crypto_acomp_streams struct was made to rely on
having the alloc_ctx and free_ctx operations defined in the same order
as the scomp_alg struct. But in that same commit, the alloc_ctx and
free_ctx members of scomp_alg may be randomized by structure layout
randomization, since they are contained in a pure ops structure
(containing only function pointers). If the pointers within scomp_alg
are randomized, but those in crypto_acomp_streams are not, then
the order may no longer match. This fixes the problem by removing the
union from scomp_alg so that both crypto_acomp_streams and scomp_alg
will share the same definition of alloc_ctx and free_ctx, ensuring
they will always have the same layout.


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