[PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE

[PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE

[Jason Wang]

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

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, 2 insertions(+)

diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 1883d61..6051a5f 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -466,6 +466,8 @@ 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 * sizeof(void *) > KMALLOC_MAX_SIZE)
+		return NULL;
 	return kcalloc(size, sizeof(void *), gfp);
 }
 
-- 
2.7.4

[PATCH V4 2/2] 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 | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 6051a5f..b884b77 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -464,11 +464,14 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
 	__PTR_RING_PEEK_CALL_v; \
 })
 
+/* Not all gfp_t flags (besides GFP_KERNEL) are allowed. See
+ * documentation for vmalloc for which of them are legal.
+ */
 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);
+	return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
 }
 
 static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)
@@ -603,7 +606,7 @@ static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
 	spin_unlock(&(r)->producer_lock);
 	spin_unlock_irqrestore(&(r)->consumer_lock, flags);
 
-	kfree(old);
+	kvfree(old);
 
 	return 0;
 }
@@ -643,7 +646,7 @@ static inline int ptr_ring_resize_multiple(struct ptr_ring **rings,
 	}
 
 	for (i = 0; i < nrings; ++i)
-		kfree(queues[i]);
+		kvfree(queues[i]);
 
 	kfree(queues);
 
@@ -651,7 +654,7 @@ static inline int ptr_ring_resize_multiple(struct ptr_ring **rings,
 
 nomem:
 	while (--i >= 0)
-		kfree(queues[i]);
+		kvfree(queues[i]);
 
 	kfree(queues);
 
@@ -666,7 +669,7 @@ static inline void ptr_ring_cleanup(struct ptr_ring *r, void (*destroy)(void *))
 	if (destroy)
 		while ((ptr = ptr_ring_consume(r)))
 			destroy(ptr);
-	kfree(r->queue);
+	kvfree(r->queue);
 }
 
 #endif /* _LINUX_PTR_RING_H  */
-- 
2.7.4

Re: [PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE

[Michael S. Tsirkin]

On Fri, Feb 09, 2018 at 05:45:49PM +0800, Jason Wang wrote:
> To avoid slab to warn about exceeded size, fail early if queue
> occupies more than KMALLOC_MAX_SIZE.
> 
> Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
> 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, 2 insertions(+)
> 
> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
> index 1883d61..6051a5f 100644
> --- a/include/linux/ptr_ring.h
> +++ b/include/linux/ptr_ring.h
> @@ -466,6 +466,8 @@ 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 * sizeof(void *) > KMALLOC_MAX_SIZE)
> +		return NULL;
>  	return kcalloc(size, sizeof(void *), gfp);
>  }
>  
> -- 
> 2.7.4

Re: [PATCH V4 2/2] ptr_ring: try vmalloc() when kmalloc() fails

[Michael S. Tsirkin]

On Fri, Feb 09, 2018 at 05:45:50PM +0800, Jason Wang wrote:
> This patch switch to use kvmalloc_array() for using a vmalloc()
> fallback to help in case kmalloc() fails.

Above isn't really saying anything about the motivation, it
just explains what kvmalloc_array does.

How about:

Switch ptr_ring from kmalloc to kvmalloc. This way it can support larger
ring sizes.

> 
> Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")

I don't see this as a bugfix - it's more of an enhancement.

Do we need this in net or can we defer this to net-next?

I'm not sure myself. For now

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> Signed-off-by: Jason Wang <jasowang@redhat.com>


> ---
>  include/linux/ptr_ring.h | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
> index 6051a5f..b884b77 100644
> --- a/include/linux/ptr_ring.h
> +++ b/include/linux/ptr_ring.h
> @@ -464,11 +464,14 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
>  	__PTR_RING_PEEK_CALL_v; \
>  })
>  
> +/* Not all gfp_t flags (besides GFP_KERNEL) are allowed. See
> + * documentation for vmalloc for which of them are legal.
> + */
>  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);
> +	return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
>  }
>  
>  static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)
> @@ -603,7 +606,7 @@ static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
>  	spin_unlock(&(r)->producer_lock);
>  	spin_unlock_irqrestore(&(r)->consumer_lock, flags);
>  
> -	kfree(old);
> +	kvfree(old);
>  
>  	return 0;
>  }
> @@ -643,7 +646,7 @@ static inline int ptr_ring_resize_multiple(struct ptr_ring **rings,
>  	}
>  
>  	for (i = 0; i < nrings; ++i)
> -		kfree(queues[i]);
> +		kvfree(queues[i]);
>  
>  	kfree(queues);
>  
> @@ -651,7 +654,7 @@ static inline int ptr_ring_resize_multiple(struct ptr_ring **rings,
>  
>  nomem:
>  	while (--i >= 0)
> -		kfree(queues[i]);
> +		kvfree(queues[i]);
>  
>  	kfree(queues);
>  
> @@ -666,7 +669,7 @@ static inline void ptr_ring_cleanup(struct ptr_ring *r, void (*destroy)(void *))
>  	if (destroy)
>  		while ((ptr = ptr_ring_consume(r)))
>  			destroy(ptr);
> -	kfree(r->queue);
> +	kvfree(r->queue);
>  }
>  
>  #endif /* _LINUX_PTR_RING_H  */
> -- 
> 2.7.4

Re: [PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE

[David Miller]

From: Jason Wang <jasowang@redhat.com>
Date: Fri,  9 Feb 2018 17:45:49 +0800

> To avoid slab to warn about exceeded size, fail early if queue
> occupies more than KMALLOC_MAX_SIZE.
> 
> Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Applied.

Re: [PATCH V4 2/2] ptr_ring: try vmalloc() when kmalloc() fails

[David Miller]

From: Jason Wang <jasowang@redhat.com>
Date: Fri,  9 Feb 2018 17:45:50 +0800

> 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>

Applied.

Re: [PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE

[Eric Biggers]

Hi Jason,

On Fri, Feb 09, 2018 at 05:45:49PM +0800, Jason Wang wrote:
> To avoid slab to warn about exceeded size, fail early if queue
> occupies more than KMALLOC_MAX_SIZE.
> 
> 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, 2 insertions(+)
> 
> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
> index 1883d61..6051a5f 100644
> --- a/include/linux/ptr_ring.h
> +++ b/include/linux/ptr_ring.h
> @@ -466,6 +466,8 @@ 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 * sizeof(void *) > KMALLOC_MAX_SIZE)
> +		return NULL;

Are you sure that size can't be over 0x40000000?  The proper way to write this
(safe from integer overflow) would be:

	if (size > KMALLOC_MAX_SIZE / sizeof(void *))
		return NULL;

- Eric

Re: [PATCH V4 2/2] ptr_ring: try vmalloc() when kmalloc() fails

[Jason Wang]

On 2018年02月09日 23:53, Michael S. Tsirkin wrote:
> On Fri, Feb 09, 2018 at 05:45:50PM +0800, Jason Wang wrote:
>> This patch switch to use kvmalloc_array() for using a vmalloc()
>> fallback to help in case kmalloc() fails.
> Above isn't really saying anything about the motivation, it
> just explains what kvmalloc_array does.
>
> How about:
>
> Switch ptr_ring from kmalloc to kvmalloc. This way it can support larger
> ring sizes.
>
>> Reported-by:syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
>> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
> I don't see this as a bugfix - it's more of an enhancement.
>
> Do we need this in net or can we defer this to net-next?

Consider they are users of tx_queue_len of more than 1000000 from google 
searching. We'd better have this in -net.

Thanks

>
> I'm not sure myself. For now
>
> Acked-by: Michael S. Tsirkin<mst@redhat.com>
>

Re: [PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE

[Jason Wang]

On 2018年02月11日 03:32, Eric Biggers wrote:
> Hi Jason,
>
> On Fri, Feb 09, 2018 at 05:45:49PM +0800, Jason Wang wrote:
>> To avoid slab to warn about exceeded size, fail early if queue
>> occupies more than KMALLOC_MAX_SIZE.
>>
>> 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, 2 insertions(+)
>>
>> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
>> index 1883d61..6051a5f 100644
>> --- a/include/linux/ptr_ring.h
>> +++ b/include/linux/ptr_ring.h
>> @@ -466,6 +466,8 @@ 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 * sizeof(void *) > KMALLOC_MAX_SIZE)
>> +		return NULL;
> Are you sure that size can't be over 0x40000000?  The proper way to write this
> (safe from integer overflow) would be:
>
> 	if (size > KMALLOC_MAX_SIZE / sizeof(void *))
> 		return NULL;
>
> - Eric

Good catch.

Will post a fix.

Thanks