[PATCH 4.9 10/84] ptr_ring: use kmalloc_array()

Greg Kroah-Hartman
2017-08-28T08:49:27Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 81fbfe8adaf38d4f5a98c19bebfd41c5d6acaee8 ]

As found by syzkaller, malicious users can set whatever tx_queue_len
on a tun device and eventually crash the kernel.

Lets remove the ALIGN(XXX, SMP_CACHE_BYTES) thing since a small
ring buffer is not fast anyway.

Fixes: 2e0ab8ca83c1 ("ptr_ring: array based FIFO for pointers")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/ptr_ring.h | 9 +++++----
include/linux/skb_array.h | 3 ++-
2 files changed, 7 insertions(+), 5 deletions(-)

--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -340,9 +340,9 @@ static inline void *ptr_ring_consume_bh(
__PTR_RING_PEEK_CALL_v; \
})

-static inline void **__ptr_ring_init_queue_alloc(int size, gfp_t gfp)
+static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
{
- return kzalloc(ALIGN(size * sizeof(void *), SMP_CACHE_BYTES), gfp);
+ return kcalloc(size, sizeof(void *), gfp);
}

static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
@@ -417,7 +417,8 @@ static inline int ptr_ring_resize(struct
* In particular if you consume ring in interrupt or BH context, you must
* disable interrupts/BH when doing so.
*/
-static inline int ptr_ring_resize_multiple(struct ptr_ring **rings, int nrings,
+static inline int ptr_ring_resize_multiple(struct ptr_ring **rings,
+ unsigned int nrings,
int size,
gfp_t gfp, void (*destroy)(void *))
{
@@ -425,7 +426,7 @@ static inline int ptr_ring_resize_multip
void ***queues;
int i;

- queues = kmalloc(nrings * sizeof *queues, gfp);
+ queues = kmalloc_array(nrings, sizeof(*queues), gfp);
if (!queues)
goto noqueues;

--- a/include/linux/skb_array.h
+++ b/include/linux/skb_array.h
@@ -162,7 +162,8 @@ static inline int skb_array_resize(struc
}

static inline int skb_array_resize_multiple(struct skb_array **rings,
- int nrings, int size, gfp_t gfp)
+ int nrings, unsigned int size,
+ gfp_t gfp)
{
BUILD_BUG_ON(offsetof(struct skb_array, ring));
return ptr_ring_resize_multiple((struct ptr_ring **)rings,