Merge tag '6.7-rc5-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull smb client fixes from Steve French:
 "Address OOBs and NULL dereference found by Dr. Morris's recent
  analysis and fuzzing.

  All marked for stable as well"

* tag '6.7-rc5-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  smb: client: fix OOB in smb2_query_reparse_point()
  smb: client: fix NULL deref in asn1_ber_decoder()
  smb: client: fix potential OOBs in smb2_parse_contexts()
  smb: client: fix OOB in receive_encrypted_standard()

5 files changed, 109 insertions, 79 deletions

diff --git a/fs/smb/client/cached_dir.c b/fs/smb/client/cached_dir.c
index 59f6b8e32cc97..d64a306a414be 100644
--- a/fs/smb/client/cached_dir.c
+++ b/fs/smb/client/cached_dir.c
@@ -291,16 +291,23 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
 	oparms.fid->mid = le64_to_cpu(o_rsp->hdr.MessageId);
 #endif /* CIFS_DEBUG2 */
 
-	rc = -EINVAL;
+
 	if (o_rsp->OplockLevel != SMB2_OPLOCK_LEVEL_LEASE) {
 		spin_unlock(&cfids->cfid_list_lock);
+		rc = -EINVAL;
+		goto oshr_free;
+	}
+
+	rc = smb2_parse_contexts(server, rsp_iov,
+				 &oparms.fid->epoch,
+				 oparms.fid->lease_key,
+				 &oplock, NULL, NULL);
+	if (rc) {
+		spin_unlock(&cfids->cfid_list_lock);
 		goto oshr_free;
 	}
 
-	smb2_parse_contexts(server, o_rsp,
-			    &oparms.fid->epoch,
-			    oparms.fid->lease_key, &oplock,
-			    NULL, NULL);
+	rc = -EINVAL;
 	if (!(oplock & SMB2_LEASE_READ_CACHING_HE)) {
 		spin_unlock(&cfids->cfid_list_lock);
 		goto oshr_free;
diff --git a/fs/smb/client/smb2misc.c b/fs/smb/client/smb2misc.c
index 32dfa0f7a78c3..e20b4354e703b 100644
--- a/fs/smb/client/smb2misc.c
+++ b/fs/smb/client/smb2misc.c
@@ -313,6 +313,9 @@ static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
 char *
 smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *shdr)
 {
+	const int max_off = 4096;
+	const int max_len = 128 * 1024;
+
 	*off = 0;
 	*len = 0;
 
@@ -384,29 +387,20 @@ smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *shdr)
 	 * Invalid length or offset probably means data area is invalid, but
 	 * we have little choice but to ignore the data area in this case.
 	 */
-	if (*off > 4096) {
-		cifs_dbg(VFS, "offset %d too large, data area ignored\n", *off);
-		*len = 0;
-		*off = 0;
-	} else if (*off < 0) {
-		cifs_dbg(VFS, "negative offset %d to data invalid ignore data area\n",
-			 *off);
+	if (unlikely(*off < 0 || *off > max_off ||
+		     *len < 0 || *len > max_len)) {
+		cifs_dbg(VFS, "%s: invalid data area (off=%d len=%d)\n",
+			 __func__, *off, *len);
 		*off = 0;
 		*len = 0;
-	} else if (*len < 0) {
-		cifs_dbg(VFS, "negative data length %d invalid, data area ignored\n",
-			 *len);
-		*len = 0;
-	} else if (*len > 128 * 1024) {
-		cifs_dbg(VFS, "data area larger than 128K: %d\n", *len);
+	} else if (*off == 0) {
 		*len = 0;
 	}
 
 	/* return pointer to beginning of data area, ie offset from SMB start */
-	if ((*off != 0) && (*len != 0))
+	if (*off > 0 && *len > 0)
 		return (char *)shdr + *off;
-	else
-		return NULL;
+	return NULL;
 }
 
 /*
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index fcfb6566b899f..8f6f0a38b8868 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -3003,7 +3003,7 @@ static int smb2_query_reparse_point(const unsigned int xid,
 	struct kvec *rsp_iov;
 	struct smb2_ioctl_rsp *ioctl_rsp;
 	struct reparse_data_buffer *reparse_buf;
-	u32 plen;
+	u32 off, count, len;
 
 	cifs_dbg(FYI, "%s: path: %s\n", __func__, full_path);
 
@@ -3084,16 +3084,22 @@ static int smb2_query_reparse_point(const unsigned int xid,
 	 */
 	if (rc == 0) {
 		/* See MS-FSCC 2.3.23 */
+		off = le32_to_cpu(ioctl_rsp->OutputOffset);
+		count = le32_to_cpu(ioctl_rsp->OutputCount);
+		if (check_add_overflow(off, count, &len) ||
+		    len > rsp_iov[1].iov_len) {
+			cifs_tcon_dbg(VFS, "%s: invalid ioctl: off=%d count=%d\n",
+				      __func__, off, count);
+			rc = -EIO;
+			goto query_rp_exit;
+		}
 
-		reparse_buf = (struct reparse_data_buffer *)
-			((char *)ioctl_rsp +
-			 le32_to_cpu(ioctl_rsp->OutputOffset));
-		plen = le32_to_cpu(ioctl_rsp->OutputCount);
-
-		if (plen + le32_to_cpu(ioctl_rsp->OutputOffset) >
-		    rsp_iov[1].iov_len) {
-			cifs_tcon_dbg(FYI, "srv returned invalid ioctl len: %d\n",
-				 plen);
+		reparse_buf = (void *)((u8 *)ioctl_rsp + off);
+		len = sizeof(*reparse_buf);
+		if (count < len ||
+		    count < le16_to_cpu(reparse_buf->ReparseDataLength) + len) {
+			cifs_tcon_dbg(VFS, "%s: invalid ioctl: off=%d count=%d\n",
+				      __func__, off, count);
 			rc = -EIO;
 			goto query_rp_exit;
 		}
@@ -4943,6 +4949,7 @@ receive_encrypted_standard(struct TCP_Server_Info *server,
 	struct smb2_hdr *shdr;
 	unsigned int pdu_length = server->pdu_size;
 	unsigned int buf_size;
+	unsigned int next_cmd;
 	struct mid_q_entry *mid_entry;
 	int next_is_large;
 	char *next_buffer = NULL;
@@ -4971,14 +4978,15 @@ receive_encrypted_standard(struct TCP_Server_Info *server,
 	next_is_large = server->large_buf;
 one_more:
 	shdr = (struct smb2_hdr *)buf;
-	if (shdr->NextCommand) {
+	next_cmd = le32_to_cpu(shdr->NextCommand);
+	if (next_cmd) {
+		if (WARN_ON_ONCE(next_cmd > pdu_length))
+			return -1;
 		if (next_is_large)
 			next_buffer = (char *)cifs_buf_get();
 		else
 			next_buffer = (char *)cifs_small_buf_get();
-		memcpy(next_buffer,
-		       buf + le32_to_cpu(shdr->NextCommand),
-		       pdu_length - le32_to_cpu(shdr->NextCommand));
+		memcpy(next_buffer, buf + next_cmd, pdu_length - next_cmd);
 	}
 
 	mid_entry = smb2_find_mid(server, buf);
@@ -5002,8 +5010,8 @@ one_more:
 	else
 		ret = cifs_handle_standard(server, mid_entry);
 
-	if (ret == 0 && shdr->NextCommand) {
-		pdu_length -= le32_to_cpu(shdr->NextCommand);
+	if (ret == 0 && next_cmd) {
+		pdu_length -= next_cmd;
 		server->large_buf = next_is_large;
 		if (next_is_large)
 			server->bigbuf = buf = next_buffer;
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 20634fc6d4f09..c571760ad39a1 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -2236,17 +2236,18 @@ parse_posix_ctxt(struct create_context *cc, struct smb2_file_all_info *info,
 		 posix->nlink, posix->mode, posix->reparse_tag);
 }
 
-void
-smb2_parse_contexts(struct TCP_Server_Info *server,
-		    struct smb2_create_rsp *rsp,
-		    unsigned int *epoch, char *lease_key, __u8 *oplock,
-		    struct smb2_file_all_info *buf,
-		    struct create_posix_rsp *posix)
+int smb2_parse_contexts(struct TCP_Server_Info *server,
+			struct kvec *rsp_iov,
+			unsigned int *epoch,
+			char *lease_key, __u8 *oplock,
+			struct smb2_file_all_info *buf,
+			struct create_posix_rsp *posix)
 {
-	char *data_offset;
+	struct smb2_create_rsp *rsp = rsp_iov->iov_base;
 	struct create_context *cc;
-	unsigned int next;
-	unsigned int remaining;
+	size_t rem, off, len;
+	size_t doff, dlen;
+	size_t noff, nlen;
 	char *name;
 	static const char smb3_create_tag_posix[] = {
 		0x93, 0xAD, 0x25, 0x50, 0x9C,
@@ -2255,45 +2256,63 @@ smb2_parse_contexts(struct TCP_Server_Info *server,
 	};
 
 	*oplock = 0;
-	data_offset = (char *)rsp + le32_to_cpu(rsp->CreateContextsOffset);
-	remaining = le32_to_cpu(rsp->CreateContextsLength);
-	cc = (struct create_context *)data_offset;
+
+	off = le32_to_cpu(rsp->CreateContextsOffset);
+	rem = le32_to_cpu(rsp->CreateContextsLength);
+	if (check_add_overflow(off, rem, &len) || len > rsp_iov->iov_len)
+		return -EINVAL;
+	cc = (struct create_context *)((u8 *)rsp + off);
 
 	/* Initialize inode number to 0 in case no valid data in qfid context */
 	if (buf)
 		buf->IndexNumber = 0;
 
-	while (remaining >= sizeof(struct create_context)) {
-		name = le16_to_cpu(cc->NameOffset) + (char *)cc;
-		if (le16_to_cpu(cc->NameLength) == 4 &&
-		    strncmp(name, SMB2_CREATE_REQUEST_LEASE, 4) == 0)
-			*oplock = server->ops->parse_lease_buf(cc, epoch,
-							   lease_key);
-		else if (buf && (le16_to_cpu(cc->NameLength) == 4) &&
-		    strncmp(name, SMB2_CREATE_QUERY_ON_DISK_ID, 4) == 0)
-			parse_query_id_ctxt(cc, buf);
-		else if ((le16_to_cpu(cc->NameLength) == 16)) {
-			if (posix &&
-			    memcmp(name, smb3_create_tag_posix, 16) == 0)
+	while (rem >= sizeof(*cc)) {
+		doff = le16_to_cpu(cc->DataOffset);
+		dlen = le32_to_cpu(cc->DataLength);
+		if (check_add_overflow(doff, dlen, &len) || len > rem)
+			return -EINVAL;
+
+		noff = le16_to_cpu(cc->NameOffset);
+		nlen = le16_to_cpu(cc->NameLength);
+		if (noff + nlen >= doff)
+			return -EINVAL;
+
+		name = (char *)cc + noff;
+		switch (nlen) {
+		case 4:
+			if (!strncmp(name, SMB2_CREATE_REQUEST_LEASE, 4)) {
+				*oplock = server->ops->parse_lease_buf(cc, epoch,
+								       lease_key);
+			} else if (buf &&
+				   !strncmp(name, SMB2_CREATE_QUERY_ON_DISK_ID, 4)) {
+				parse_query_id_ctxt(cc, buf);
+			}
+			break;
+		case 16:
+			if (posix && !memcmp(name, smb3_create_tag_posix, 16))
 				parse_posix_ctxt(cc, buf, posix);
+			break;
+		default:
+			cifs_dbg(FYI, "%s: unhandled context (nlen=%zu dlen=%zu)\n",
+				 __func__, nlen, dlen);
+			if (IS_ENABLED(CONFIG_CIFS_DEBUG2))
+				cifs_dump_mem("context data: ", cc, dlen);
+			break;
 		}
-		/* else {
-			cifs_dbg(FYI, "Context not matched with len %d\n",
-				le16_to_cpu(cc->NameLength));
-			cifs_dump_mem("Cctxt name: ", name, 4);
-		} */
-
-		next = le32_to_cpu(cc->Next);
-		if (!next)
+
+		off = le32_to_cpu(cc->Next);
+		if (!off)
 			break;
-		remaining -= next;
-		cc = (struct create_context *)((char *)cc + next);
+		if (check_sub_overflow(rem, off, &rem))
+			return -EINVAL;
+		cc = (struct create_context *)((u8 *)cc + off);
 	}
 
 	if (rsp->OplockLevel != SMB2_OPLOCK_LEVEL_LEASE)
 		*oplock = rsp->OplockLevel;
 
-	return;
+	return 0;
 }
 
 static int
@@ -3124,8 +3143,8 @@ SMB2_open(const unsigned int xid, struct cifs_open_parms *oparms, __le16 *path,
 	}
 
 
-	smb2_parse_contexts(server, rsp, &oparms->fid->epoch,
-			    oparms->fid->lease_key, oplock, buf, posix);
+	rc = smb2_parse_contexts(server, &rsp_iov, &oparms->fid->epoch,
+				 oparms->fid->lease_key, oplock, buf, posix);
 creat_exit:
 	SMB2_open_free(&rqst);
 	free_rsp_buf(resp_buftype, rsp);
diff --git a/fs/smb/client/smb2proto.h b/fs/smb/client/smb2proto.h
index 46eff9ec302aa..0e371f7e2854b 100644
--- a/fs/smb/client/smb2proto.h
+++ b/fs/smb/client/smb2proto.h
@@ -251,11 +251,13 @@ extern int smb3_validate_negotiate(const unsigned int, struct cifs_tcon *);
 
 extern enum securityEnum smb2_select_sectype(struct TCP_Server_Info *,
 					enum securityEnum);
-extern void smb2_parse_contexts(struct TCP_Server_Info *server,
-				struct smb2_create_rsp *rsp,
-				unsigned int *epoch, char *lease_key,
-				__u8 *oplock, struct smb2_file_all_info *buf,
-				struct create_posix_rsp *posix);
+int smb2_parse_contexts(struct TCP_Server_Info *server,
+			struct kvec *rsp_iov,
+			unsigned int *epoch,
+			char *lease_key, __u8 *oplock,
+			struct smb2_file_all_info *buf,
+			struct create_posix_rsp *posix);
+
 extern int smb3_encryption_required(const struct cifs_tcon *tcon);
 extern int smb2_validate_iov(unsigned int offset, unsigned int buffer_length,
 			     struct kvec *iov, unsigned int min_buf_size);