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 3899B4A4EE0 for ; Thu, 24 Sep 2026 15:29:29 +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=1790263771; cv=none; b=sXoWDMjdWeImDqo0vM867FeiwX4jI1hG7zvaemSzF25qpnCFRRras8TgdDop27c7Gx9/ZVkOUVpamx9Dbby1eBybasO7C4YOtM2BwSiWj2BJvSjudAXmx39KlSw/T8bTsaV5HaTdmsH4cJk7gnMnWNmK4W2G75Lo3Q1tavnhJrg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790263771; c=relaxed/simple; bh=CBuH2HcmMuZSA6pXl1p21fyXqdF2V95PM3/bFVlrRIs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=qO1VHrkQ1kiyBa8t4RTaAjNHPcNFAJoF/9M5IykYW4F5IFM5nBVrAsPre5ihdIz2budljCgvZXFKao3JQGG/JNbMZly5sk0qzpFDrNUQjPQND4Az3Jo5J0zB8YIUCgFj/38YT9ijtyoJLbNba2PVPUV//vx5kHCL7rGOJdorUdo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zXWA2xnu; 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="zXWA2xnu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3B711F00899; Thu, 24 Sep 2026 15:29:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790263769; bh=YwuAWboqpmMZ4CepuhSAEecAQsgtbGEXJZo2awMwMuY=; h=From:To:Cc:Subject:Date:Reply-To; b=zXWA2xnuKCuQf2kN0M1DEfL0pahGguCSmLx4HmY4sAJKtOAnvzS0jSgWZ1LKe6AoK TNvNTA75rLhU3TLD20TIDD2EOwatupkNc3AZC1ZFGH4NXQpYjoMRyz27bu1BXbGwlE IxFbU8mVx3V7psy6DNmeZ/NWcAG7dalQQvtvDUbE= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-93228: svcrdma: Reject Write/Reply chunks with segcount 0 Date: Thu, 24 Sep 2026 17:28:44 +0200 Message-ID: <2026092441-CVE-2026-93228-7632@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=3740; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=IbngY3uHyQ/y/Ya9aUPwn7wT/GQXsymwQCH0WqKpszs=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlbHVdWX8pJFDouq20ve8dg5hrmGXMn7KjYbjPzsJ/P8 prqn6xrOmJZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAip+MZ5tlMWFFUyvbizTT7 ie5ndjx1cViXUsYwh/uuoUqwhoeCx94lZ5vf+qs9enJHDgA= 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: svcrdma: Reject Write/Reply chunks with segcount 0 A peer can send a Write or Reply chunk whose segcount field is zero. xdr_check_write_chunk() only rejects segcount > rc_maxpages, so zero passes the range check, and xdr_inline_decode(stream, 0) returns the current (non-NULL) cursor without advancing. The function returns true and pcl_alloc_write() then links a struct svc_rdma_chunk with ch_segcount == 0 onto rc_write_pcl or rc_reply_pcl. An earlier patch in this series made pcl_for_each_segment() safe for ch_segcount == 0, so this no longer drives the memory walk it used to. Rejecting the malformed frame at the decode boundary is still worthwhile as defense in depth: it keeps degenerate zero-segment chunks off the parsed chunk lists entirely, so any future consumer that walks ch_segments directly cannot observe one, and it makes the zero-floor easy to backport to trees where the macro change is more intrusive. RFC 8166 has no meaning for a Write/Reply chunk that describes no remote buffer, so no legitimate client is affected. xdr_check_reply_chunk() funnels Reply chunks through xdr_check_write_chunk() and inherits the same rejection. pcl_alloc_write() also links each chunk onto the parsed chunk list before filling its segment array. If a future change weakens the segcount-0 rejection, an incomplete chunk is visible to consumers during the fill loop. Reorder so that list_add_tail() follows the segment fill loop, ensuring only fully-populated chunks appear on the list. The Linux kernel CVE team has assigned CVE-2026-93228 to this issue. Affected and fixed versions =========================== Issue introduced in 5.11 with commit 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 and fixed in 6.12.111 with commit fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f Issue introduced in 5.11 with commit 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 and fixed in 6.18.50 with commit a798714b58041e88716db3bf8fb03ae13eecd54a Issue introduced in 5.11 with commit 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 and fixed in 7.2.4 with commit 45dbdb2637b7fc5f1355b588780d2a7fb0516805 Issue introduced in 5.11 with commit 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 and fixed in 7.3-rc1 with commit 9808eb7656666acc7291bae9ab6b987bd16e47e0 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-2026-93228 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/sunrpc/xprtrdma/svc_rdma_pcl.c net/sunrpc/xprtrdma/svc_rdma_recvfrom.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/fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f https://git.kernel.org/stable/c/a798714b58041e88716db3bf8fb03ae13eecd54a https://git.kernel.org/stable/c/45dbdb2637b7fc5f1355b588780d2a7fb0516805 https://git.kernel.org/stable/c/9808eb7656666acc7291bae9ab6b987bd16e47e0