relay: prevent integer overflow in relay_open()

BugLink: http://bugs.launchpad.net/bugs/937915

commit f6302f1bcd75a042df69866d98b8d775a668f8f1 upstream.

"subbuf_size" and "n_subbufs" come from the user and they need to be
capped to prevent an integer overflow.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Brad Figg <brad.figg@canonical.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/kernel/relay.c b/kernel/relay.c
index 859ea5a9605..2c242fb2368 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -164,10 +164,14 @@ depopulate:
  */
 static struct rchan_buf *relay_create_buf(struct rchan *chan)
 {
-        struct rchan_buf *buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL);
-        if (!buf)
+        struct rchan_buf *buf;
+
+        if (chan->n_subbufs > UINT_MAX / sizeof(size_t *))
                 return NULL;
 
+        buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL);
+        if (!buf)
+                return NULL;
         buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
         if (!buf->padding)
                 goto free_buf;
@@ -574,6 +578,8 @@ struct rchan *relay_open(const char *base_filename,
 
         if (!(subbuf_size && n_subbufs))
                 return NULL;
+        if (subbuf_size > UINT_MAX / n_subbufs)
+                return NULL;
 
         chan = kzalloc(sizeof(struct rchan), GFP_KERNEL);
         if (!chan)