Commit bbc8a99e authored Jul 30, 2020 by Peilin Ye Committed by David S. Miller Jul 31, 2020

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: f037590f ("rds: fix a leak of kernel memory")
Fixes: bdbe6fbc ("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>

parent dc096288

net/rds/recv.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -450,12 +450,13 @@ static int rds_still_queued(struct rds_sock rs, struct rds_incoming inc,
		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

Admin message