The patch below does not apply to the 4.4-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 <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 350be257ea83029daee974c72b1fe2e6f1f8e615 Mon Sep 17 00:00:00 2001
From: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Date: Mon, 10 Apr 2017 10:31:33 -0700
Subject: [PATCH] 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: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
CC: Stable <stable@xxxxxxxxxxxxxxx>
Acked-by: Sachin Prabhu <sprabhu@xxxxxxxxxx>
Signed-off-by: Steve French <smfrench@xxxxxxxxx>
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index ec5e5e514fdd..97e5d236d265 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -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,
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 967b92631807..5d21f00ae341 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -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;
}
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 7b12a727947e..152e37f2ad92 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -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;
}