From: Peilin Ye yepeilin.cs@gmail.com
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: 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/rds/recv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/rds/recv.c +++ b/net/rds/recv.c @@ -455,12 +455,13 @@ static int rds_still_queued(struct rds_s 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