4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Wang <jasow...@redhat.com>

commit 6e6e41c3112276288ccaf80c70916779b84bb276 upstream.

To avoid slab to warn about exceeded size, fail early if queue
occupies more than KMALLOC_MAX_SIZE.

Reported-by: syzbot+e4d4f9ddd42955397...@syzkaller.appspotmail.com
Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
Signed-off-by: Jason Wang <jasow...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 include/linux/ptr_ring.h |    2 ++
 1 file changed, 2 insertions(+)

--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -351,6 +351,8 @@ static inline void *ptr_ring_consume_bh(
 
 static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
 {
+       if (size * sizeof(void *) > KMALLOC_MAX_SIZE)
+               return NULL;
        return kcalloc(size, sizeof(void *), gfp);
 }
 


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