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Commit 350be257 authored by Pavel Shilovsky's avatar Pavel Shilovsky Committed by Steve French
Browse files

CIFS: Fix null pointer deref during read resp processing 



Currently during receiving a read response mid->resp_buf can be
NULL when it is being passed to cifs_discard_remaining_data() from
cifs_readv_discard(). Fix it by always passing server->smallbuf
instead and initializing mid->resp_buf at the end of read response
processing.

Signed-off-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Acked-by: default avatarSachin Prabhu <sprabhu@redhat.com>
Signed-off-by: default avatarSteve French <smfrench@gmail.com>
parent c08e611b

fs/cifs/cifsproto.h

+1 −2
Original line number Diff line number Diff line
@@ -79,8 +79,7 @@ extern void cifs_delete_mid(struct mid_q_entry *mid); 
extern void cifs_wake_up_task(struct mid_q_entry *mid);

extern int cifs_handle_standard(struct TCP_Server_Info *server,

				struct mid_q_entry *mid);

extern int cifs_discard_remaining_data(struct TCP_Server_Info *server,

				       char *buf);

extern int cifs_discard_remaining_data(struct TCP_Server_Info *server);

extern int cifs_call_async(struct TCP_Server_Info *server,

			struct smb_rqst *rqst,

			mid_receive_t *receive, mid_callback_t *callback,

fs/cifs/cifssmb.c

+8 −7
Original line number Diff line number Diff line
@@ -1400,9 +1400,9 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock, 
 * current bigbuf.

 */

int

cifs_discard_remaining_data(struct TCP_Server_Info *server, char *buf)

cifs_discard_remaining_data(struct TCP_Server_Info *server)

{

	unsigned int rfclen = get_rfc1002_length(buf);

	unsigned int rfclen = get_rfc1002_length(server->smallbuf);

	int remaining = rfclen + 4 - server->total_read;



	while (remaining > 0) {
@@ -1426,8 +1426,10 @@ cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid) 
	int length;

	struct cifs_readdata *rdata = mid->callback_data;



	length = cifs_discard_remaining_data(server, mid->resp_buf);

	length = cifs_discard_remaining_data(server);

	dequeue_mid(mid, rdata->result);

	mid->resp_buf = server->smallbuf;

	server->smallbuf = NULL;

	return length;

}
@@ -1459,7 +1461,7 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid) 


	if (server->ops->is_status_pending &&

	    server->ops->is_status_pending(buf, server, 0)) {

		cifs_discard_remaining_data(server, buf);

		cifs_discard_remaining_data(server);

		return -1;

	}
@@ -1519,9 +1521,6 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid) 
	cifs_dbg(FYI, "0: iov_base=%p iov_len=%u\n",

		 rdata->iov[0].iov_base, server->total_read);



	mid->resp_buf = server->smallbuf;

	server->smallbuf = NULL;



	/* how much data is in the response? */

	data_len = server->ops->read_data_length(buf);

	if (data_offset + data_len > buflen) {
@@ -1544,6 +1543,8 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid) 
		return cifs_readv_discard(server, mid);



	dequeue_mid(mid, false);

	mid->resp_buf = server->smallbuf;

	server->smallbuf = NULL;

	return length;

}

fs/cifs/smb2ops.c

+2 −2
Original line number Diff line number Diff line
@@ -2195,7 +2195,7 @@ receive_encrypted_read(struct TCP_Server_Info *server, struct mid_q_entry **mid) 
	if (rc)

		goto free_pages;



	rc = cifs_discard_remaining_data(server, buf);

	rc = cifs_discard_remaining_data(server);

	if (rc)

		goto free_pages;
@@ -2221,7 +2221,7 @@ receive_encrypted_read(struct TCP_Server_Info *server, struct mid_q_entry **mid) 
	kfree(pages);

	return rc;

discard_data:

	cifs_discard_remaining_data(server, buf);

	cifs_discard_remaining_data(server);

	goto free_pages;

}