rds: rds_msg_zcopy should return error of null rm->data.op_mmp_znotifier

if either or both of MSG_ZEROCOPY and SOCK_ZEROCOPY have not been
specified, the rm->data.op_mmp_znotifier allocation will be skipped.
In this case, it is invalid ot pass down a cmsghdr with
RDS_CMSG_ZCOPY_COOKIE, so return EINVAL from rds_msg_zcopy for this
case.

Reported-by: syzbot+f893ae7bb2f6456dfbc3@syzkaller.appspotmail.com
Fixes: 0cebaccef3ac ("rds: zerocopy Tx support.")
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/rds/send.c b/net/rds/send.c
index 79d158b..acad042 100644 (file)
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -941,7 +941,8 @@ static int rds_cmsg_zcopy(struct rds_sock *rs, struct rds_message *rm,
 {
        u32 *cookie;
 
-       if (cmsg->cmsg_len < CMSG_LEN(sizeof(*cookie)))
+       if (cmsg->cmsg_len < CMSG_LEN(sizeof(*cookie)) ||
+           !rm->data.op_mmp_znotifier)
                return -EINVAL;
        cookie = CMSG_DATA(cmsg);
        rm->data.op_mmp_znotifier->z_cookie = *cookie;