Re: [PATCH] net: rds: fix memory leak in rds_recvmsg
From: Haakon Bugge <hidden>
Date: 2021-06-08 07:11:38
Also in:
lkml, netdev
On 7 Jun 2021, at 21:41, Pavel Skripkin [off-list ref] wrote:
Syzbot reported memory leak in rds. The problem
was in unputted refcount in case of error.
int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
int msg_flags)
{
...
if (!rds_next_incoming(rs, &inc)) {
...
}
After this "if" inc refcount incremented and
if (rds_cmsg_recv(inc, msg, rs)) {
ret = -EFAULT;
goto out;
}
...
out:
return ret;
}
in case of rds_cmsg_recv() fail the refcount won't be
decremented. And it's easy to see from ftrace log, that
rds_inc_addref() don't have rds_inc_put() pair in
rds_recvmsg() after rds_cmsg_recv()
1) | rds_recvmsg() {
1) 3.721 us | rds_inc_addref();
1) 3.853 us | rds_message_inc_copy_to_user();
1) + 10.395 us | rds_cmsg_recv();
1) + 34.260 us | }
Fixes: bdbe6fbc6a2f ("RDS: recv.c")
Reported-and-tested-by: syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <redacted>Thank for your commit and analyses. One small nit below.
quoted hunk ↗ jump to hunk
--- net/rds/recv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/net/rds/recv.c b/net/rds/recv.c index 4db109fb6ec2..3fa16c339bfe 100644 --- a/net/rds/recv.c +++ b/net/rds/recv.c@@ -714,7 +714,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,if (rds_cmsg_recv(inc, msg, rs)) { ret = -EFAULT; - goto out; + goto out_put;
Would a simple "break;" do it here and no need for the next hunk? Thxs, Håkon
quoted hunk ↗ jump to hunk
} rds_recvmsg_zcookie(rs, msg);@@ -740,6 +740,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,break; } +out_put: if (inc) rds_inc_put(inc); -- 2.31.1