From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793817653; b=PKg9KR6H+gNDWCx+Dwqt1xD4HdM7eyE4i9CBbj9gwByYOAn7h2xcWP5DaWS9Qgx3fRir 9XNuLfz+T2kjut1ZdaffwStMIwjNSfgdW+WqvVAYiOEDCiDWUwoqHWWOkkKMdtVFqTQV5 YsoemUNVjM0h3/L5XHvHMMRu3ULjOpMyvFE4+dzx+T/d+Qq8f4PUgibn4Rq+ER24ByauH LRweCx5rM5MvVlivcBXZMb/HSOs5amGUKMdVkg79+i4ub5+NHU7jIkytEvgKNLU/m1nv1 Yw7w2Gh6ib639cfT+EcpDCRU5yAT/adQ08vq9miNDuoS0PUt+JaAMFCouKLVyfeYuPA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793817653; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=+4isRBVNC+b2Ea3Sol+RWxRI/sV5w7waClARqKCZJZ8=; b=3pusgtsoxf/cQhYEiqqZxiTpxDL+yg9yCAlYmqKZbWogtGSVR8/2yZkWVMA7m5oRBIL/ MWal9ngb/yezn4rjhie9KlzNdjBzOZtUWMn85Dtfc3+fpepkTm+TMW4Qkbi+nIgHlC6D9 yC/SYZV/nblItYNdwc80eGFFnoLttaXn8YKVhsq0jJ5V5XDGv8pZVxAiwsHLwKLIlSUY2 etXSW7JyVf2w1TCY6ifGeuberSnOF4sf5TVIsFpGaDjX73r6kIjCD3xTo1RTGWpbnxJm4 X432qdxNSvKjhnRO3ODrjimEI+DtOZnm8dCfN4Mmr7wFhY9WxG712jgZt8LnZSYFVng== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=wY1fLASe; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A6D4D606D816 for ; Wed, 4 Nov 2026 18:40:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=wY1fLASe Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D2051F00919; Wed, 4 Nov 2026 18:40:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793817652; bh=+4isRBVNC+b2Ea3Sol+RWxRI/sV5w7waClARqKCZJZ8=; h=Subject:To:Cc:From:Date; b=wY1fLASeXRE476Jmanzzcaho9UuxxCUESkMO/JFYN8qwIdhX8hFsPKVGiipYCzZIy LlcB1qLfhSvPQJ9dEySh51SxJ90gGy38lgms7QCHWdaTPpHLFPmuIk9M1y/p/yxytY Me/CKY+Q2vpPfqT4ACT4SRKwrakfQ42McfDjcoy8= Subject: FAILED: patch "[PATCH] smb: client: validate the data area in SMB2_read()" failed to apply to 6.18-stable tree To: suruurism@gmail.com,linkinjeon@kernel.org,pc@manguebit.org Cc: From: Date: Wed, 04 Nov 2026 13:40:50 -0500 Message-ID: <2026110450-wreckage-support-bb8c@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x 2ec9cdf469dd32bcf33073aeb30c08e9356e0ca1 # git commit -s git send-email --to '' --in-reply-to '2026110450-wreckage-support-bb8c@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 2ec9cdf469dd32bcf33073aeb30c08e9356e0ca1 Mon Sep 17 00:00:00 2001 From: Abdifatah Suruur Date: Thu, 22 Oct 2026 06:53:29 +0300 Subject: [PATCH] smb: client: validate the data area in SMB2_read() SMB2_read() copies le32_to_cpu(rsp->DataLength) bytes from (char *)rsp + rsp->DataOffset without checking that the range lies within the response actually received. A READ response with DataOffset == 0 makes smb2_get_data_area_len() zero the data length, so smb2_check_message() accepts a frame as short as the fixed response, while SMB2_read() still uses the server-supplied DataLength, capped only by CIFS_MAX_MSGSIZE and the caller's length. A malicious server can answer the synchronous read used by the mfsymlinks (or SFU) symlink parser with an 81-byte READ response carrying DataOffset 0 and DataLength 1067, making the client copy 1067 bytes from a 448-byte receive object (KASAN slab-out-of-bounds; up to 16 KiB in the general case). Clamp a zero (or header-overlapping) DataOffset to read_rsp_size, as handle_read_data() does for the asynchronous path, and reject the response unless DataOffset + DataLength fits within rsp_iov.iov_len. The SMB1 helper was fixed the same way in 5be5bdda5863. Fixes: d8e050398d23 ("CIFS: Add readpage support for SMB2") Cc: stable@vger.kernel.org Signed-off-by: Abdifatah Suruur Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index 06a6ca0dc098..f85595136ef8 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -4948,6 +4948,7 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms, struct kvec iov[1]; struct kvec rsp_iov; unsigned int total_len; + u16 data_offset; int flags = CIFS_LOG_ERROR; struct cifs_ses *ses = io_parms->tcon->ses; @@ -5007,8 +5008,29 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms, *nbytes = 0; } + data_offset = rsp->DataOffset; + if (data_offset < io_parms->server->vals->read_rsp_size) { + /* + * win2k8 sometimes sends an offset of 0 when the read is beyond + * the EOF. Treat it as if the data starts just after the header, + * as handle_read_data() does. + */ + cifs_dbg(FYI, "data offset %u inside read response header\n", + data_offset); + data_offset = io_parms->server->vals->read_rsp_size; + } + + /* The data area must lie within the response actually received */ + if (*nbytes && (size_t)data_offset + *nbytes > rsp_iov.iov_len) { + cifs_dbg(FYI, "bad data offset %u length %u for response of %zu\n", + data_offset, *nbytes, rsp_iov.iov_len); + rc = smb_EIO2(smb_eio_trace_read_bad_offset, + data_offset, *nbytes); + *nbytes = 0; + } + if (*buf) { - memcpy(*buf, (char *)rsp + rsp->DataOffset, *nbytes); + memcpy(*buf, (char *)rsp + data_offset, *nbytes); free_rsp_buf(resp_buftype, rsp_iov.iov_base); } else if (resp_buftype != CIFS_NO_BUFFER) { *buf = rsp_iov.iov_base;