[net] ptr_ring: prevent integer overflow when calculating size

Message ID 1518319692-5421-1-git-send-email-jasowang@redhat.com
State Accepted
Delegated to: David Miller
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Series
  • [net] ptr_ring: prevent integer overflow when calculating size
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Commit Message

Jason Wang Feb. 11, 2018, 3:28 a.m.
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>
---
 include/linux/ptr_ring.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Michael S. Tsirkin Feb. 11, 2018, 10:02 p.m. | #1
On Sun, Feb 11, 2018 at 11:28:12AM +0800, Jason Wang wrote:
> 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>

> ---
>  include/linux/ptr_ring.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
> index b884b77..e633522 100644
> --- a/include/linux/ptr_ring.h
> +++ b/include/linux/ptr_ring.h
> @@ -469,7 +469,7 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
>   */
>  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 kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
>  }
> -- 
> 2.7.4
David Miller Feb. 12, 2018, 3:34 a.m. | #2
From: Jason Wang <jasowang@redhat.com>
Date: Sun, 11 Feb 2018 11:28:12 +0800

> 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>

Applied and queued up for -stable, thanks Jason.

Patch

diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index b884b77..e633522 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -469,7 +469,7 @@  static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
  */
 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 kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
 }