[PATCH 4.9 84/91] sctp: free cmd->obj.chunk for the unprocessed SCTP_CMD_REPLY

From: Greg Kroah-Hartman
Date: Sat Jan 11 2020 - 05:06:24 EST


From: Xin Long <lucien.xin@xxxxxxxxx>

[ Upstream commit be7a7729207797476b6666f046d765bdf9630407 ]

This patch is to fix a memleak caused by no place to free cmd->obj.chunk
for the unprocessed SCTP_CMD_REPLY. This issue occurs when failing to
process a cmd while there're still SCTP_CMD_REPLY cmds on the cmd seq
with an allocated chunk in cmd->obj.chunk.

So fix it by freeing cmd->obj.chunk for each SCTP_CMD_REPLY cmd left on
the cmd seq when any cmd returns error. While at it, also remove 'nomem'
label.

Reported-by: syzbot+107c4aff5f392bf1517f@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sctp/sm_sideeffect.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)

--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -1321,8 +1321,10 @@ static int sctp_cmd_interpreter(sctp_eve
/* Generate an INIT ACK chunk. */
new_obj = sctp_make_init_ack(asoc, chunk, GFP_ATOMIC,
0);
- if (!new_obj)
- goto nomem;
+ if (!new_obj) {
+ error = -ENOMEM;
+ break;
+ }

sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
SCTP_CHUNK(new_obj));
@@ -1344,7 +1346,8 @@ static int sctp_cmd_interpreter(sctp_eve
if (!new_obj) {
if (cmd->obj.chunk)
sctp_chunk_free(cmd->obj.chunk);
- goto nomem;
+ error = -ENOMEM;
+ break;
}
sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
SCTP_CHUNK(new_obj));
@@ -1391,8 +1394,10 @@ static int sctp_cmd_interpreter(sctp_eve

/* Generate a SHUTDOWN chunk. */
new_obj = sctp_make_shutdown(asoc, chunk);
- if (!new_obj)
- goto nomem;
+ if (!new_obj) {
+ error = -ENOMEM;
+ break;
+ }
sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
SCTP_CHUNK(new_obj));
break;
@@ -1721,11 +1726,17 @@ static int sctp_cmd_interpreter(sctp_eve
break;
}

- if (error)
+ if (error) {
+ cmd = sctp_next_cmd(commands);
+ while (cmd) {
+ if (cmd->verb == SCTP_CMD_REPLY)
+ sctp_chunk_free(cmd->obj.chunk);
+ cmd = sctp_next_cmd(commands);
+ }
break;
+ }
}

-out:
/* If this is in response to a received chunk, wait until
* we are done with the packet to open the queue so that we don't
* send multiple packets in response to a single request.
@@ -1740,8 +1751,5 @@ out:
sp->data_ready_signalled = 0;

return error;
-nomem:
- error = -ENOMEM;
- goto out;
}