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 3C789542ECD for ; Thu, 17 Sep 2026 16:42:01 +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=1789663323; cv=none; b=IVTyQlx5jVwMcBM0ZEzArfhNW6p9RcJaw/qItCcz2wiJM7Uax4KZ5qPrJLLQQp6OYtStmQdB94c/KRrD4be3IeSdw0C5U0BpKP+56qbYFMsTNxCoOkj5Y6T+06BGIMasXwwhXqE1zsJyz9BvUWsqhZHOLoaSNivcbd5QMEk98AM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789663323; c=relaxed/simple; bh=gFvVSRBRT/o8SwHke9D5buyxtN2O6eDUCAt3IY1tSW8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hKHKmlj3ubbK4/zCUN/KRZmU83nqH46vpm84mHHeiQAUnHP1XYoPAcXDRJWSJxKamQ24wFF6A+zTEGDNsr7Nq8EDrUqI5GEiOyckiQG8xhHiiPe9IB4vCEcvDxMiLRhL2FBvxjJyHQQvZy+mIeyMu82cnaCCi60yjsXF867/Jv0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iXkOUc8f; 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="iXkOUc8f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FF471F0089A; Thu, 17 Sep 2026 16:42:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789663321; bh=esSclqd4LXb0woGd0RLx0Bb3P4znpH13wpFumOUO/Is=; h=From:To:Cc:Subject:Date:Reply-To; b=iXkOUc8fShaJXaRYEqep/5FkACH+HArW/JWd4smqXJSVAVoLZTn65ZeNAOkUF9M/M f9A7hNJ6xz+UTrcWuxqnKdeP9wtanPdvJPPRGjBqAwuRX0yASZ0/+FoeJStVbENA0s he43F36u6D9QGSz0PWJbeuNfrRIcaoFNJA2cJF28= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-93203: batman-adv: bla: avoid CRC corruption due to parallel claim add Date: Thu, 17 Sep 2026 17:18:00 +0100 Message-ID: <2026091706-CVE-2026-93203-8a4d@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=4987; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=sFpC4mOqKdxjQ1s6b83TgkqxvO/dn5JSUrX8bLnTrHk=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlrBO5/uLBodegfFsd3V2P31SzZrtj7fc1nnZ8dtmZun Hml340vdMSyMAgyMciKKbJ82cZzdH/FIUUvQ9vTMHNYmUCGMHBxCsBEzscwzOHxXPJrxoKlH6uX mt0TM7Lzcmz+/Ilhvq/E3xRV5an7mtO3qlbITttlZHPXGgA= 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: bla: avoid CRC corruption due to parallel claim add batadv_bla_add_claim() is used to add claims and modify the backbone of claims for CLAIM frames from remote backbones and local packets. When it handles a claim, it needs to either * add the new claim's CRC to the backbone CRC * remove the already existing claim's CRC from the old backbone and add it to the new backbone But when the "new" claim code was running in parallel to the "change backbone" code, it can happen that the CRC was invalid because the backbone_gw of the claim was changed twice in the "new" claim code path: * CPU0 creates the claim for gateway A and publishes it in the claim hash. The crc16 of the address has not yet been added to A's crc at this point. * CPU1 processes a claim frame of gateway B for the same client, finds the just published claim, and performs the ownership change: it switches the pointer to B, removes the crc16 from A's crc - which never contained it - and adds it to B's crc. * CPU0 continues behind the creation branch, unconditionally switches the pointer back to A without compensating B's crc (its remove_crc is false for the creation path), and finally adds the crc16 to A's crc The CRC is then wrong for both: * claim belongs to A: but CRC is not part of backbone A's CRC * claim doesn't belong to B: CRC is still part of backbone B's CRC This wrong CRC is never recomputated from the stored claims. For local backbone claims, this can also not recovered using syncs. To avoid this, split the functionality in clear separate parts: * new claim which always adds claim CRC to the backbone CRC (but never changes the already set backbone_gw of the claim back) * update of existing claim which automatically changes the backbone_gw entry and only updates both backbone CRCs when there was an actual change The Linux kernel CVE team has assigned CVE-2026-93203 to this issue. Affected and fixed versions =========================== Issue introduced in 3.5 with commit 23721387c409087fd3b97e274f34d3ddc0970b74 and fixed in 5.10.270 with commit 3d4a9ae2c69c0fe4c3c69587288241243bb7a39b Issue introduced in 3.5 with commit 23721387c409087fd3b97e274f34d3ddc0970b74 and fixed in 5.15.221 with commit ad982d925f00d860d2467811256ffadcccd9e4a7 Issue introduced in 3.5 with commit 23721387c409087fd3b97e274f34d3ddc0970b74 and fixed in 6.1.188 with commit d5b0e7574da5a485f4dbec32a15911900a4487c2 Issue introduced in 3.5 with commit 23721387c409087fd3b97e274f34d3ddc0970b74 and fixed in 6.6.157 with commit a3e07db74f22a85aeeb51c600da5c98b9cbca11f Issue introduced in 3.5 with commit 23721387c409087fd3b97e274f34d3ddc0970b74 and fixed in 6.12.110 with commit 1d390db003cbb52cdd86837608bff3794501a5ea Issue introduced in 3.5 with commit 23721387c409087fd3b97e274f34d3ddc0970b74 and fixed in 6.18.52 with commit 8bcfa58c4277bff1882a23547c37ab08aa1de12f Issue introduced in 3.5 with commit 23721387c409087fd3b97e274f34d3ddc0970b74 and fixed in 7.2.6 with commit e54602d9e38db8573f2097d60c7ea8be0a5af1fa Issue introduced in 3.5 with commit 23721387c409087fd3b97e274f34d3ddc0970b74 and fixed in 7.3-rc1 with commit 08645ab95768b88e2ff85a89211994651710465b 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-2026-93203 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/bridge_loop_avoidance.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/3d4a9ae2c69c0fe4c3c69587288241243bb7a39b https://git.kernel.org/stable/c/ad982d925f00d860d2467811256ffadcccd9e4a7 https://git.kernel.org/stable/c/d5b0e7574da5a485f4dbec32a15911900a4487c2 https://git.kernel.org/stable/c/a3e07db74f22a85aeeb51c600da5c98b9cbca11f https://git.kernel.org/stable/c/1d390db003cbb52cdd86837608bff3794501a5ea https://git.kernel.org/stable/c/8bcfa58c4277bff1882a23547c37ab08aa1de12f https://git.kernel.org/stable/c/e54602d9e38db8573f2097d60c7ea8be0a5af1fa https://git.kernel.org/stable/c/08645ab95768b88e2ff85a89211994651710465b