From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-93138: bpf: Fix vmlinux BTF prep race in bpf_get_btf_vmlinux
Date: Thu, 17 Sep 2026 17:16:55 +0100 [thread overview]
Message-ID: <2026091753-CVE-2026-93138-0f4e@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix vmlinux BTF prep race in bpf_get_btf_vmlinux
bpf_get_btf_vmlinux() lazily parses the vmlinux BTF under the
bpf_verifier_lock, but publishes the result through a plain store
and re-checks it through a plain lockless load. Nothing orders
the stores initializing the struct btf inside btf_parse_vmlinux()
against the store publishing the pointer: On a weakly ordered
arch, a concurrent first-time caller taking the lockless fast
path could in principle observe the pointer before the parsed
contents are visible. The mutex_unlock() does not help such a
reader given it only synchronizes with a later acquisition of the
same lock. Thus, publish the pointer with smp_store_release()
and read it on the fast path with smp_load_acquire().
Acquire semantics are needed rather than a dependency-ordered
READ_ONCE(): btf_parse_vmlinux() also populates globals outside
the returned object (e.g. bpf_ctx_convert.t). An address
dependency would only order accesses performed through the
pointer and not cover other globals.
The Linux kernel CVE team has assigned CVE-2026-93138 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.5 with commit 8580ac9404f6240668a026785d7d8856f0530409 and fixed in 5.10.270 with commit f32a4a40bc635be25d6816da4bd91e9e58c31bf3
Issue introduced in 5.5 with commit 8580ac9404f6240668a026785d7d8856f0530409 and fixed in 5.15.221 with commit a7fe72d780122eb934536f1719abad445f6afdf7
Issue introduced in 5.5 with commit 8580ac9404f6240668a026785d7d8856f0530409 and fixed in 6.1.188 with commit e18a10b39c994f04e1ebd7f8fc042bb1ca8ad053
Issue introduced in 5.5 with commit 8580ac9404f6240668a026785d7d8856f0530409 and fixed in 6.6.157 with commit 978524ecfc1c539282df5858de1eec20748c6f74
Issue introduced in 5.5 with commit 8580ac9404f6240668a026785d7d8856f0530409 and fixed in 6.12.110 with commit eaf302628a78806f66d8224d6ba03fb4d5025de4
Issue introduced in 5.5 with commit 8580ac9404f6240668a026785d7d8856f0530409 and fixed in 6.18.52 with commit 2892f3f44bf865c8fb6b6c0960edec4cc91806ee
Issue introduced in 5.5 with commit 8580ac9404f6240668a026785d7d8856f0530409 and fixed in 7.2.6 with commit 86d11c594d60b255b526fa5260f669463fb1a063
Issue introduced in 5.5 with commit 8580ac9404f6240668a026785d7d8856f0530409 and fixed in 7.3-rc1 with commit 92863e678070f57c17c868e4bfa2441a5c61ad2b
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2026-93138
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
kernel/bpf/verifier.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/f32a4a40bc635be25d6816da4bd91e9e58c31bf3
https://git.kernel.org/stable/c/a7fe72d780122eb934536f1719abad445f6afdf7
https://git.kernel.org/stable/c/e18a10b39c994f04e1ebd7f8fc042bb1ca8ad053
https://git.kernel.org/stable/c/978524ecfc1c539282df5858de1eec20748c6f74
https://git.kernel.org/stable/c/eaf302628a78806f66d8224d6ba03fb4d5025de4
https://git.kernel.org/stable/c/2892f3f44bf865c8fb6b6c0960edec4cc91806ee
https://git.kernel.org/stable/c/86d11c594d60b255b526fa5260f669463fb1a063
https://git.kernel.org/stable/c/92863e678070f57c17c868e4bfa2441a5c61ad2b
reply other threads:[~2026-09-17 16:38 UTC|newest]
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