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Subject[PATCH 4.9 104/329] ptr_ring: prevent integer overflow when calculating size
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Jason Wang <jasowang@redhat.com>

[ Upstream commit 54e02162d4454a99227f520948bf4494c3d972d0 ]

Switch to use dividing to prevent integer overflow when size is too
big to calculate allocation size properly.

Reported-by: Eric Biggers <ebiggers3@gmail.com>
Fixes: 6e6e41c31122 ("ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/ptr_ring.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -351,7 +351,7 @@ 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)
+ if (size > KMALLOC_MAX_SIZE / sizeof(void *))
return NULL;
return kcalloc(size, sizeof(void *), gfp);
}

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