From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 71BD24F4738 for ; Wed, 16 Sep 2026 10:40:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789555252; cv=none; b=tTy9FfUrKRmpmWg79ldl+gPCe7GtlsfMshYek8KvhRd/iYkbjh1dr0UYnzaMgrT/FN5hbxz1c5QywgayefJ6h202tzhjAKO4Z235/2liYz1N3i7lVLRbFChAdFwbSTMDQ822c2T/S1PBi6/uDikdvujdtdwzCNCdThrK/YZtVtM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789555252; c=relaxed/simple; bh=GH4POHpOsSKS99Jh8P0Q7lPf0RR30TXXimGK11Vh0Iw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=BV2cm/ECwc0fXKogp6wb+YFZTN23U38UFwcyRNtgEwS67YNmkL39j5qau47pANBFp+CjZOZ4Ybk07rtCwbCm0jcDTFOsp8lVm13ZRhOMTHMJV3QsCOcYs7ogstD3fSxK241DqgOEj1fJiWKNEPehFNfOlH+OhdY0CjOiG9ceFpo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=me+o5KlJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="me+o5KlJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 200821F0089F; Wed, 16 Sep 2026 10:40:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789555235; bh=0Cfg04btN1HzojXOQ08sgcp2sFAMsm7eXokZ2eIbEx0=; h=From:To:Cc:Subject:Date:Reply-To; b=me+o5KlJOWxf6i6ZanBIbhIlMM4aQzMUehCDtAGUdLOO6W5psRnsHFvavC0crL7Fk 9GI6ScWiXG5W6bcmmBt2fgD0t8YImw2afeA84cofNCLaaNwBAGpT0GVVF51psWPHgG eAhA/U+7NzdClCdnz5tV9BOb5T3SkFhbIabXst1I= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89950: batman-adv: mcast: linearize skbuff for packet generation Date: Wed, 16 Sep 2026 11:31:20 +0100 Message-ID: <2026091649-CVE-2026-89950-01fd@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3053; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=/yRv1Jd48nFsjbwku0yxggecaFYVTzgWl6ypaCNDsPQ=; b=owGbwMvMwCRo6H6F97bub03G02pJDFmr8ucmGu4/UnZhg63dvc4Lu4IClkxaeH3aTC6NptijB 9TFFjSId8SyMAgyMciKKbJ82cZzdH/FIUUvQ9vTMHNYmUCGMHBxCsBE1BczzLO5udf75P3V29rO G7Fs636x+tVv92kM8+N/zD2b4DG1ctLVtT4Lu7aUCM05vhgA X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: batman-adv: mcast: linearize skbuff for packet generation batadv_mcast_forw_packet() and batadv_mcast_forw_scrape() is not only called (indirectly) by the unsharing+linearizing batadv_recv_mcast_packet() handler. When it is called (indirectly) by batadv_mcast_forw_mcsend() then it will be unshared but not linearized. The SKB_LINEAR_ASSERT() can therefore cause a fatal BUG(). The linearization should happen during the expansion of the head because the scrape function can be hit already during the initial batadv_mcast_forw_mode() selection code: * batadv_interface_tx * batadv_mcast_forw_mode * batadv_mcast_forw_mode_by_count() * batadv_mcast_forw_push() -> calls batadv_mcast_forw_expand_head() before everything else * batadv_mcast_forw_push_tvlvs() * batadv_mcast_forw_push_dests() * batadv_mcast_forw_push_adjust_padding() * batadv_mcast_forw_scrape() The Linux kernel CVE team has assigned CVE-2026-89950 to this issue. Affected and fixed versions =========================== Issue introduced in 6.8 with commit 90039133221e33964ccb4a536dad7eb0a372fff7 and fixed in 6.12.110 with commit a9603e0a7cb5e0cddc6b23af153cf7daafc5c55e Issue introduced in 6.8 with commit 90039133221e33964ccb4a536dad7eb0a372fff7 and fixed in 6.18.51 with commit c32e5e25c41201c8c3b796a4ab2c45103187091e Issue introduced in 6.8 with commit 90039133221e33964ccb4a536dad7eb0a372fff7 and fixed in 7.2.5 with commit 2879177539e3ece483a8e5406970373698e9a6c5 Issue introduced in 6.8 with commit 90039133221e33964ccb4a536dad7eb0a372fff7 and fixed in 7.3-rc1 with commit 6a30a59e2660afd03c975f1b8eae6a2301161197 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-2026-89950 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/multicast_forw.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/a9603e0a7cb5e0cddc6b23af153cf7daafc5c55e https://git.kernel.org/stable/c/c32e5e25c41201c8c3b796a4ab2c45103187091e https://git.kernel.org/stable/c/2879177539e3ece483a8e5406970373698e9a6c5 https://git.kernel.org/stable/c/6a30a59e2660afd03c975f1b8eae6a2301161197