On Tue, 8 Jun 2021 07:11:27 +0000
Haakon Bugge <haakon.bugge@xxxxxxxxxx> wrote:
>
>
> > On 7 Jun 2021, at 21:41, Pavel Skripkin <paskripkin@xxxxxxxxx>
> > 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@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx>
>
> Thank for your commit and analyses. One small nit below.
>
> > ---
> > 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
>
Sure! I'll send v2 soon. Thank you for feedback :)
With regards,
Pavel Skripkin
