From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-64089: batman-adv: tt: fix negative last_changeset_len
Date: Sun, 19 Jul 2026 17:39:11 +0200 [thread overview]
Message-ID: <2026071917-CVE-2026-64089-321e@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
batman-adv: tt: fix negative last_changeset_len
batadv_piv_tt::last_changeset_len len was declared as s16, but the field is
never intended to hold a negative value. When a value greater than 32767 is
assigned, it wraps to a negative signed integer.
In batadv_send_my_tt_response(), last_changeset_len is temporarily widened
to s32. The incorrectly negative s16 value propagates into the s32, causing
batadv_tt_prepare_tvlv_local_data() to allocate a full sized buffer but
populates only a small portion of it with the collected changeset. All
remaining bits are kept uninitialized.
Using an u16 avoids this type confusion and ensures that no (negative) sign
extension is performed in batadv_send_my_tt_response().
The Linux kernel CVE team has assigned CVE-2026-64089 to this issue.
Affected and fixed versions
===========================
Issue introduced in 3.1 with commit a73105b8d4c765d9ebfb664d0a66802127d8e4c7 and fixed in 5.10.258 with commit 6314089acf0ddf64376fdc0b1420695504c73f52
Issue introduced in 3.1 with commit a73105b8d4c765d9ebfb664d0a66802127d8e4c7 and fixed in 5.15.209 with commit 55dc41fe8821e9a849e147255ad572bc933a9d15
Issue introduced in 3.1 with commit a73105b8d4c765d9ebfb664d0a66802127d8e4c7 and fixed in 6.1.175 with commit c424e8519ac78eac5d9f4eecf06208a0d619ec14
Issue introduced in 3.1 with commit a73105b8d4c765d9ebfb664d0a66802127d8e4c7 and fixed in 6.6.142 with commit 22d59c72f4a47ffec121d0610f70d0d70c3c11c8
Issue introduced in 3.1 with commit a73105b8d4c765d9ebfb664d0a66802127d8e4c7 and fixed in 6.12.92 with commit eb235472b52ef36981c5aad330485eaf2382c53b
Issue introduced in 3.1 with commit a73105b8d4c765d9ebfb664d0a66802127d8e4c7 and fixed in 6.18.34 with commit 179eb62506a02d00370bd6478898cb632e10986c
Issue introduced in 3.1 with commit a73105b8d4c765d9ebfb664d0a66802127d8e4c7 and fixed in 7.0.11 with commit d29abf70c665730e249d2ec8e1402095ae26bcee
Issue introduced in 3.1 with commit a73105b8d4c765d9ebfb664d0a66802127d8e4c7 and fixed in 7.1 with commit fc92cdfcb295cefa4344d71a527d61b638b7bfc4
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-2026-64089
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/batman-adv/types.h
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/6314089acf0ddf64376fdc0b1420695504c73f52
https://git.kernel.org/stable/c/55dc41fe8821e9a849e147255ad572bc933a9d15
https://git.kernel.org/stable/c/c424e8519ac78eac5d9f4eecf06208a0d619ec14
https://git.kernel.org/stable/c/22d59c72f4a47ffec121d0610f70d0d70c3c11c8
https://git.kernel.org/stable/c/eb235472b52ef36981c5aad330485eaf2382c53b
https://git.kernel.org/stable/c/179eb62506a02d00370bd6478898cb632e10986c
https://git.kernel.org/stable/c/d29abf70c665730e249d2ec8e1402095ae26bcee
https://git.kernel.org/stable/c/fc92cdfcb295cefa4344d71a527d61b638b7bfc4
reply other threads:[~2026-07-19 15:45 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2026071917-CVE-2026-64089-321e@gregkh \
--to=gregkh@linuxfoundation.org \
--cc=cve@kernel.org \
--cc=gregkh@kernel.org \
--cc=linux-cve-announce@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox