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=1793932496; b=dB0dsp7HnN0pdZWPR3aaep1fJqcKbOaYHAQoV4HBNAzjsjH3t1+zQiZ+yQZX5Rydrh35 TAixIl0C2d2TU3wQEkGgCWceE+OYOpKPPHTUx1326bj2hidHyx1bvKKIFk1sAzyXemdLn XOD7WVbjVhPls66qwyZjbTPmI2+2jrA2zwK3fXDlxwHddnVJQdc53LP4qo1KpGMGVJqn8 0Q6LGo1KQL5PK4aoNpS9uGArb+ZxS2JirB44FSDaxOLr8/TohFg1PkMDzOXTev9Rx8e43 TrVkD1tv3fGo9lPtK0UWNfxGmmVIXC51l1Cob+u9wC0tKSO6TD9m9XJtaPC50vYcT9Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793932496; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=Kn0M/yCwcX8v1DPwR8zexDnpRkerdE1Hiw1W6jA/I20=; b=yTmdq86B4Q13K/IeqQFdn98+cgKekdvQA/FR+V8jCQAJ0mOiDwokCS0nv6GPF3Eo9NFr bEJTOCxkENJyxOskBlFAkilXXzmAjYIgFEJnckY3gW8lb+HCu0kWGWqVtHoEqXMF1N6Gg zn+L1Y6RkNG44y3hOHwsd88tQwE+uUOGI7vdPBiPTtLbMeubqhH9s/nwBCS3mdHknxYGM MtDfL9wKtKamNPJdf3LXHuXFdTDhzrmpRhsPeXiQhsGXYIPEtEQAxi2Zy7EvjOaIoXZAn kN8D16RXu9vOgknoNckRGAjqpaYdfu4lD25HXSXwKXvPP5dRKiL2yxivCwDRK7vpCvg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=SfGQZgEA; 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 A3B9F606A33A for ; Fri, 6 Nov 2026 02:34:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=SfGQZgEA Received: by smtp.kernel.org (Postfix) with ESMTPSA id A67401F008BE; Fri, 6 Nov 2026 02:34:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793932496; bh=Kn0M/yCwcX8v1DPwR8zexDnpRkerdE1Hiw1W6jA/I20=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=SfGQZgEAZXOTIUDa4x/mfXZbo5qYaAzOcGP3vzAEbnd/vlFVRawYFL1P5KJ5d3UAk bhINz4PSCRD7SfAwT62F1GR68wb2O2y92DUMM2x3WT6rhc9c/CEP6WEdvGPDgRvKPy 2BVCfglEc45U/RNFtwuCsu4Xm42uH+lHNZC2qJNp3zx2Hqk8NqGHf4uol0oWJvmkwu 0xvNdUNqEr3QM8z1AOxGMTb+adXt5Y1vxJ2Yu0Zui4xZXOEnFwQOxG+vY6awNgmquk EqHZhFTiCeeZcT8dJmMcAXlB2fUARIOapmRIgl3C8ikJwedaioFu/I4S3F/dPdACX/ ts6+ZWn3kGusw== From: Sasha Levin To: stable@vger.kernel.org Cc: Abdifatah Suruur , Namjae Jeon , Paulo Alcantara , Sasha Levin Subject: [PATCH 5.10.y] smb: client: validate the data area in SMB2_read() Date: Thu, 5 Nov 2026 21:34:54 -0500 Message-ID: <20261106022008.3501484-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110422-santa-book-618b@gregkh> References: <2026110422-santa-book-618b@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-Transfer-Encoding: 8bit From: Abdifatah Suruur [ Upstream commit 2ec9cdf469dd32bcf33073aeb30c08e9356e0ca1 ] 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 [ sashal: replaced smb_EIO2() with a direct rc = -EIO assignment because the tracing helper is unavailable ] Signed-off-by: Sasha Levin --- fs/cifs/smb2pdu.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index a2f1d165d8862..9380cb3ea9743 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -4162,6 +4162,7 @@ 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; @@ -4218,8 +4219,28 @@ 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 = -EIO; + *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; -- 2.53.0