rds: Prevent kernel-infoleak in rds_notify_queue_get()
rds_notify_queue_get() is potentially copying uninitialized kernel stack
memory to userspace since the compiler may leave a 4-byte hole at the end
of `cmsg`.
In 2016 we tried to fix this issue by doing `= { 0 };` on `cmsg`, which
unfortunately does not always initialize that 4-byte hole. Fix it by using
memset() instead.
Cc: stable@vger.kernel.org
Fixes: f037590fff30 ("rds: fix a leak of kernel memory")
Fixes: bdbe6fbc6a2f ("RDS: recv.c")
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rds/recv.c b/net/rds/recv.c
index c840497..aba4afe 100644
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -450,12 +450,13 @@
int rds_notify_queue_get(struct rds_sock *rs, struct msghdr *msghdr)
{
struct rds_notifier *notifier;
- struct rds_rdma_notify cmsg = { 0 }; /* fill holes with zero */
+ struct rds_rdma_notify cmsg;
unsigned int count = 0, max_messages = ~0U;
unsigned long flags;
LIST_HEAD(copy);
int err = 0;
+ memset(&cmsg, 0, sizeof(cmsg)); /* fill holes with zero */
/* put_cmsg copies to user space and thus may sleep. We can't do this
* with rs_lock held, so first grab as many notifications as we can stuff
