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 259103D9026 for ; Fri, 4 Sep 2026 16:00:50 +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=1788537652; cv=none; b=WGCmp+ePEG/cqWw6rgZ8C/+6vThdKmuVuixt4gDjNCoOzAW+9FdlZ00JEwZhqOdj3KsRe2v++bGFIwP6PXOoPpJTTthiwETeOeBo+CXbVPqU+MrKm8F2W4ejUEjPxOIssQ1Jy9G3w51706xLv33SzavPNFN8xWP4EbygQ3zoQcE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788537652; c=relaxed/simple; bh=bd2+OXXfQLUlr4JXDJUFeWWDjNOoQOQZ8Xfl96oWZt4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=J3sjZgZ92nXheTDCFcXZQ2rISjY0picBW0WhTrZ6iv5AWQLPOskIBCKpe8xGlY1IsMw/RjxRB9ELjVFZjK+qhn+e/yVi+xWEBqVIwA5XDbt/SRe1/Qh5NdgPxE1qWT/loKm8htrR/MZdviVoGriGF7i+Vck52Wq8EMprlfHRj8U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Kaz1H8zW; 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="Kaz1H8zW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D5AE1F00A3E; Fri, 4 Sep 2026 16:00:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788537650; bh=GDDlRu6ul1zQcNwVUykPszex/ovLzqjiPrjyOmQoPdc=; h=From:To:Cc:Subject:Date:Reply-To; b=Kaz1H8zW7JVANizSKXFrEGugrLnoddF1amalTvQ7cw95RZLvnbkjzZWanlp28B5a1 vzrA5kA2/AN5zEEqYyQa+Iw08l4oV+xbtsR7skGqpjR8XZsweqsxY4mc52JeUKGQGE 4fzei4jJaMVpdMZ9aIzRfQGXFBg/MfrGPWrTlKbc= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-80839: batman-adv: reject unrepresentable multicast TVLV offsets Date: Fri, 4 Sep 2026 17:53:06 +0200 Message-ID: <2026090457-CVE-2026-80839-49f6@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=3414; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=g5NnYm4y5xneT1QcOLmrM5U4jbEwaq3cCwhfPwMftd4=; b=owGbwMvMwCRo6H6F97bub03G02pJDFmzXkYu1UueoznzZHqoEPsC2amn5ab+m2/4rZgj8qdbg FqL1NO0jlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjIIz+GBUtZH2am3XQKfKed PyP4x4H2srrD8xnmaRbMOBqxXDv+jO43gZ4n3gd783aJAAA= 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: reject unrepresentable multicast TVLV offsets The network and transport header fields in struct sk_buff are 16-bit offsets from skb->head, and U16_MAX is reserved as the unset transport header value. batadv_tvlv_call_handler() sets both fields from a received multicast TVLV without checking whether the TVLV end is representable. If the end offset exceeds the field's range, skb_set_transport_header() truncates it so that the transport header precedes the network header. The negative difference is then returned by skb_network_header_len() as a large u32. batadv_mcast_forw_packet() consequently accepts an oversized multicast tracker and accesses memory beyond the skb data. Add skb_set_transport_header_careful(), an offset-aware counterpart to skb_reset_transport_header_careful(), which validates the final head-relative offset before assigning it. Use the new helper in batadv_tvlv_call_handler() and reject unrepresentable TVLVs before setting the network header. The Linux kernel CVE team has assigned CVE-2026-80839 to this issue. Affected and fixed versions =========================== Issue introduced in 6.8 with commit 07afe1ba288c04280622fa002ed385f1ac0b6fe6 and fixed in 6.12.108 with commit da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2 Issue introduced in 6.8 with commit 07afe1ba288c04280622fa002ed385f1ac0b6fe6 and fixed in 6.18.49 with commit 916ec741e65af072b98e475feaad98c063da1b7c Issue introduced in 6.8 with commit 07afe1ba288c04280622fa002ed385f1ac0b6fe6 and fixed in 7.1.13 with commit 1b466746fe109127fd983100a228cdd1f1f6ece2 Issue introduced in 6.8 with commit 07afe1ba288c04280622fa002ed385f1ac0b6fe6 and fixed in 7.2.3 with commit 2b46baa591d0a7c16b62f150917187e70d053be6 Issue introduced in 6.8 with commit 07afe1ba288c04280622fa002ed385f1ac0b6fe6 and fixed in 7.3-rc1 with commit f12c2de4f542e3220e17e0606f492110064f04cb 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-2026-80839 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: include/linux/skbuff.h net/batman-adv/tvlv.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/da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2 https://git.kernel.org/stable/c/916ec741e65af072b98e475feaad98c063da1b7c https://git.kernel.org/stable/c/1b466746fe109127fd983100a228cdd1f1f6ece2 https://git.kernel.org/stable/c/2b46baa591d0a7c16b62f150917187e70d053be6 https://git.kernel.org/stable/c/f12c2de4f542e3220e17e0606f492110064f04cb