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=1793907579; b=sTAITf+aBwc5bvoCj34ORxB6kKZr+vAV9HlLM5XS7I/7KuvsbYCUc2pS7BKQpvNwM1mT cTVJWpSEZT99XL4uQDrbZbJYTWb+qG9EtQKOwPJTVlyFe7nqbWU4wUrH/dJUSjXzkbVO4 ketEVP7yjmxaroKhdIEsR/lclQC9XWDB/XI7gyet/kzwGsdrEqJXvG16dZLEUKX5fQqJ7 6BUiC0uOqphjK62O/J2mtjVQJuY+b13Onvm1oZp5dkejMrnNijMuEGo9mFFppw2j93b5K n0ZQja6+pQ7TKNPwGYTQC5TyiP/jwSqFx+g8F6Z29L4RNvvVSoDNoGOfc8LcnFMnZHA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793907579; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=lFlbRgvyGo/ACoQo4M/CMATt8ojZGtm6zxlOMxYeXAg=; b=KZOa1pWBjdCXmJuEXJ46lXHz11NoZ6MYydHk8p2JsWBZS9oMG/r+WkwRTkmYU3atitzX nX0wznc26JGXQCx2vcaMMNh137zSajmZdOa+tTj+ZMPY8V6UC5jtY6zSgsFShTrf5uiau Hebdy38IiAJC1VB+i3rrw8j7hpz9AD4l0tQchw4v8i6JvXowpP2+Bi1wNyIVrTFR+kW3w wMrWuQ7H1QkP2jcQ3JkpgfdzLcwX0YqljAj6wAzPKgGfsimc4TSZw4r03Q19DCV0DLG7c YOsQDHXHWSX3mpPm9zu7kcGs1CQWKng9mDz5ZEZCtByrFDvKHPeheV6EEOwfmmCwZ6w== 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=RPLx3mZg; 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 D37D9607112F for ; Thu, 5 Nov 2026 19:39:38 +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=RPLx3mZg Received: by smtp.kernel.org (Postfix) with ESMTPSA id 230E61F0089F; Thu, 5 Nov 2026 19:39:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793907578; bh=lFlbRgvyGo/ACoQo4M/CMATt8ojZGtm6zxlOMxYeXAg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=RPLx3mZg/06xtlXlEgxli+YFXX+U1hZFD0Iir+t7fb8hpiTq8xmpLg1u3riy+NaeO /sk62ThAgnnp89iCyWmazng+8aeG1fM4gr+NIqwObey35jdfGxVr7qzwddzvFqEhWZ DNXqsLsTrpm2ixTh5HrXegnkkyJtULKQmA7rHR6St9aF1KxZOcv3n0SvZCLkpwMbV2 uiGzuuGNw/4zoqLAR8O1c6LzviVIf98/bNcBd4cpehfeiV/P72y5mo/6lxWV0Jd+tK cFmja7ZbN7nKiBac6b0f10KAbOlPisWzCUBwJKR+ECKPbwZRrjV67xvz1LXUm01vle yoJseGx/KzeGg== From: Sasha Levin To: stable@vger.kernel.org Cc: Diego Oliva , David Howells , Paulo Alcantara , Sasha Levin Subject: [PATCH 6.12.y] smb: client: reject FIND data areas that run past the received response Date: Thu, 5 Nov 2026 14:39:36 -0500 Message-ID: <20261105190314.2629909-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110456-awry-fastness-1fdf@gregkh> References: <2026110456-awry-fastness-1fdf@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: Diego Oliva [ Upstream commit 29bd6773187cb5c1bbbdf90d677c6add7d58af26 ] CIFSFindFirst() and CIFSFindNext() take the directory entries of a TRANS2_FIND_FIRST2 or TRANS2_FIND_NEXT2 response from DataOffset for DataCount bytes. validate_t2() bounds DataOffset at 1024 and ParameterCount + DataCount by the byte count, and nothing compares DataOffset + DataCount with the number of bytes SendReceive() copied into the buffer. smb_init() places the request and the response in the same cifs_request allocation and cifs_buf_get() clears only the start of it, so a short response whose data area extends past its end has srch_entries_start point at bytes of the request that was just sent, or at whatever the allocation held before, and those bytes are parsed as directory entries. cifs_readdir() and find_cifs_entry() walk the entries with nxt_dir_entry(), which checks every entry but the first of a response against the end of the SMB; cifs_query_path_info() and cifs_backup_query_path_info() read the first entry with no check at all. Those reads stay inside the allocation, but what they return is not part of the response. The last entry, which LastNameOffset locates relative to the data area, is bounded against the received response by an earlier patch of this series, as is every entry that cifs_fill_dirent() parses; the walk itself and the two query functions are not. SMB1 is not negotiated by default; reaching this code requires an explicit vers=1.0 mount. Reject a response whose data area extends past the received length, with the -EINVAL that validate_t2() returns for the other malformed transaction responses. cifs_query_path_info() and cifs_backup_query_path_info() still read a whole entry from a data area that may be smaller than one; that is not changed here. A conforming server is not affected. The data block of a transaction response is part of the SMB, so DataOffset + DataCount cannot exceed the smbCalcSize() bytes that SendReceive() copies; coalesce_t2() appends each secondary response to the data area and adds its length to both DataCount and the byte count, which keeps that relation. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Assisted-by: Bynario AI Signed-off-by: Diego Oliva Reviewed-by: David Howells Signed-off-by: Paulo Alcantara [ sashal: adjusted declaration context to account for the missing in_len variable ] Signed-off-by: Sasha Levin --- fs/smb/client/cifssmb.c | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-) diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c index 3795fdfebb519..603a9f6f22179 100644 --- a/fs/smb/client/cifssmb.c +++ b/fs/smb/client/cifssmb.c @@ -4004,8 +4004,9 @@ CIFSFindFirst(const unsigned int xid, struct cifs_tcon *tcon, /* level 257 SMB_ */ TRANSACTION2_FFIRST_REQ *pSMB = NULL; TRANSACTION2_FFIRST_RSP *pSMBr = NULL; - T2_FFIRST_RSP_PARMS *parms; + unsigned int data_off, data_count; struct nls_table *nls_codepage; + T2_FFIRST_RSP_PARMS *parms; unsigned int lnoff; __u16 params, byte_count; int bytes_returned = 0; @@ -4124,11 +4125,19 @@ CIFSFindFirst(const unsigned int xid, struct cifs_tcon *tcon, return rc; } + data_off = le16_to_cpu(pSMBr->t2.DataOffset); + data_count = le16_to_cpu(pSMBr->t2.DataCount); + if (data_off + data_count > (unsigned int)bytes_returned) { + cifs_dbg(VFS, "%s: data area offset %u count %u past response length %d\n", + __func__, data_off, data_count, bytes_returned); + cifs_buf_release(pSMB); + return -EINVAL; + } + psrch_inf->unicode = !!(pSMBr->hdr.Flags2 & SMBFLG2_UNICODE); psrch_inf->ntwrk_buf_start = (char *)pSMBr; psrch_inf->smallBuf = false; - psrch_inf->srch_entries_start = (char *)&pSMBr->hdr.Protocol + - le16_to_cpu(pSMBr->t2.DataOffset); + psrch_inf->srch_entries_start = (char *)&pSMBr->hdr.Protocol + data_off; parms = (T2_FFIRST_RSP_PARMS *)((char *)&pSMBr->hdr.Protocol + le16_to_cpu(pSMBr->t2.ParameterOffset)); @@ -4161,8 +4170,9 @@ int CIFSFindNext(const unsigned int xid, struct cifs_tcon *tcon, { TRANSACTION2_FNEXT_REQ *pSMB = NULL; TRANSACTION2_FNEXT_RSP *pSMBr = NULL; - T2_FNEXT_RSP_PARMS *parms; + unsigned int data_off, data_count; unsigned int name_len; + T2_FNEXT_RSP_PARMS *parms; unsigned int lnoff; __u16 params, byte_count; char *response_data; @@ -4245,13 +4255,22 @@ int CIFSFindNext(const unsigned int xid, struct cifs_tcon *tcon, cifs_buf_release(pSMB); return rc; } + + data_off = le16_to_cpu(pSMBr->t2.DataOffset); + data_count = le16_to_cpu(pSMBr->t2.DataCount); + if (data_off + data_count > (unsigned int)bytes_returned) { + cifs_dbg(VFS, "%s: data area offset %u count %u past response length %d\n", + __func__, data_off, data_count, bytes_returned); + cifs_buf_release(pSMB); + return -EINVAL; + } + /* BB fixme add lock for file (srch_info) struct here */ psrch_inf->unicode = !!(pSMBr->hdr.Flags2 & SMBFLG2_UNICODE); response_data = (char *)&pSMBr->hdr.Protocol + le16_to_cpu(pSMBr->t2.ParameterOffset); parms = (T2_FNEXT_RSP_PARMS *)response_data; - response_data = (char *)&pSMBr->hdr.Protocol + - le16_to_cpu(pSMBr->t2.DataOffset); + response_data = (char *)&pSMBr->hdr.Protocol + data_off; if (psrch_inf->smallBuf) cifs_small_buf_release(psrch_inf->ntwrk_buf_start); -- 2.53.0