Message-ID: <2025102820-CVE-2025-40078-258f@gregkh>
Date: Tue, 28 Oct 2025 12:48:55 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40078: bpf: Explicitly check accesses to bpf_sock_addr

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

bpf: Explicitly check accesses to bpf_sock_addr

Syzkaller found a kernel warning on the following sock_addr program:

    0: r0 = 0
    1: r2 = *(u32 *)(r1 +60)
    2: exit

which triggers:

    verifier bug: error during ctx access conversion (0)

This is happening because offset 60 in bpf_sock_addr corresponds to an
implicit padding of 4 bytes, right after msg_src_ip4. Access to this
padding isn't rejected in sock_addr_is_valid_access and it thus later
fails to convert the access.

This patch fixes it by explicitly checking the various fields of
bpf_sock_addr in sock_addr_is_valid_access.

I checked the other ctx structures and is_valid_access functions and
didn't find any other similar cases. Other cases of (properly handled)
padding are covered in new tests in a subsequent patch.

The Linux kernel CVE team has assigned CVE-2025-40078 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.18 with commit 1cedee13d25ab118d325f95588c1a084e9317229 and fixed in 5.15.195 with commit 6d8b1a21fd5c34622b0c3893c61e4a38d8ba53ec
	Issue introduced in 4.18 with commit 1cedee13d25ab118d325f95588c1a084e9317229 and fixed in 6.1.156 with commit 4f00858cd9bbbdf67159e28b85a8ca9e77c83622
	Issue introduced in 4.18 with commit 1cedee13d25ab118d325f95588c1a084e9317229 and fixed in 6.6.112 with commit cdeafacb4f9ff261a96baef519e29480fd7b1019
	Issue introduced in 4.18 with commit 1cedee13d25ab118d325f95588c1a084e9317229 and fixed in 6.12.53 with commit fe9d33f0470350558cb08cecb54cf2267b3a45d2
	Issue introduced in 4.18 with commit 1cedee13d25ab118d325f95588c1a084e9317229 and fixed in 6.17.3 with commit ad8b4fe5617e3c85fc23267f02500c4f3bf0ff69
	Issue introduced in 4.18 with commit 1cedee13d25ab118d325f95588c1a084e9317229 and fixed in 6.18-rc1 with commit 6fabca2fc94d33cdf7ec102058983b086293395f

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-2025-40078
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:
	net/core/filter.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/6d8b1a21fd5c34622b0c3893c61e4a38d8ba53ec
	https://git.kernel.org/stable/c/4f00858cd9bbbdf67159e28b85a8ca9e77c83622
	https://git.kernel.org/stable/c/cdeafacb4f9ff261a96baef519e29480fd7b1019
	https://git.kernel.org/stable/c/fe9d33f0470350558cb08cecb54cf2267b3a45d2
	https://git.kernel.org/stable/c/ad8b4fe5617e3c85fc23267f02500c4f3bf0ff69
	https://git.kernel.org/stable/c/6fabca2fc94d33cdf7ec102058983b086293395f

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