[PATCH 3.16 159/245] sctp: free cmd->obj.chunk for the unprocessed SCTP_CMD_REPLY

Ben Hutchings
2020-04-23T23:14:08Z

From: Xin Long <lucien.xin@gmail.com>

commit be7a7729207797476b6666f046d765bdf9630407 upstream.

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@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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
@@ -1327,8 +1327,10 @@ 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));
@@ -1350,7 +1352,8 @@ 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));
@@ -1397,8 +1400,10 @@ 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;
@@ -1727,11 +1732,17 @@ 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.
@@ -1742,8 +1753,5 @@ out:
} else if (local_cork)
error = sctp_outq_uncork(&asoc->outqueue);
return error;
-nomem:
- error = -ENOMEM;
- goto out;
}