[PATCH] rds: fix crash in rds_info_getsockopt()

[John Hubbard]

The conversion to pin_user_pages() had a bug: it overlooked
the case of allocation of pages failing. Fix that by restoring
an equivalent check.

Reported-by: syzbot+118ac0af4ac7f785a45b@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: dbfe7d74376e ("rds: convert get_user_pages() --> pin_user_pages()")

Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-rdma@xxxxxxxxxxxxxxx
Cc: rds-devel@xxxxxxxxxxxxxx
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
 net/rds/info.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/rds/info.c b/net/rds/info.c
index e1d63563e81c..b6b46a8214a0 100644
--- a/net/rds/info.c
+++ b/net/rds/info.c
@@ -234,7 +234,8 @@ int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval,
 		ret = -EFAULT;
 
 out:
-	unpin_user_pages(pages, nr_pages);
+	if (pages)
+		unpin_user_pages(pages, nr_pages);
 	kfree(pages);
 
 	return ret;
-- 
2.26.2