[PATCH net V2 1/2] ptr_ring: try vmalloc() when kmalloc() fails

[PATCH net V2 1/2] ptr_ring: try vmalloc() when kmalloc() fails

[Jason Wang]

This patch switch to use kvmalloc_array() for using a vmalloc()
fallback to help in case kmalloc() fails.

Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
Signed-off-by: Jason Wang <jasowang@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 1883d61..9c3b748 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -466,7 +466,7 @@ 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)
 {
-	return kcalloc(size, sizeof(void *), gfp);
+	return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
 }
 
 static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)
-- 
2.7.4

[PATCH net V2 2/2] ptr_ring: fail on large queue size (>64K)

[Jason Wang]

We need limit the maximum size of queue, otherwise it may cause
several side effects e.g slab will warn when the size exceeds
KMALLOC_MAX_SIZE. Using KMALLOC_MAX_SIZE still looks too so this patch
tries to limit it to 64K. This value could be revisited if we found a
real case that needs more.

Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 include/linux/ptr_ring.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 9c3b748..2520daa 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -44,6 +44,8 @@ struct ptr_ring {
 	void **queue;
 };
 
+#define PTR_RING_MAX_ALLOC 65536
+
 /* Note: callers invoking this in a loop must use a compiler barrier,
  * for example cpu_relax().
  *
@@ -466,6 +468,8 @@ 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 > PTR_RING_MAX_ALLOC)
+		return NULL;
 	return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
 }
 
-- 
2.7.4

Re: [PATCH net V2 1/2] ptr_ring: try vmalloc() when kmalloc() fails

[Jason Wang]

On 2018年02月08日 11:21, Jason Wang wrote:
> This patch switch to use kvmalloc_array() for using a vmalloc()
> fallback to help in case kmalloc() fails.
>
> Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
> Signed-off-by: Jason Wang <jasowang@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 1883d61..9c3b748 100644
> --- a/include/linux/ptr_ring.h
> +++ b/include/linux/ptr_ring.h
> @@ -466,7 +466,7 @@ 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)
>   {
> -	return kcalloc(size, sizeof(void *), gfp);
> +	return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
>   }
>   
>   static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)

Forget the kvfree() ...

Will post V3.

Sorry.