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Commit 2ec69499 authored by Peilin Ye's avatar Peilin Ye Committed by Greg Kroah-Hartman
Browse files

rds: Prevent kernel-infoleak in rds_notify_queue_get() 



commit bbc8a99e952226c585ac17477a85ef1194501762 upstream.

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: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarPeilin Ye <yepeilin.cs@gmail.com>
Acked-by: default avatarSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6a942842

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