[V4,1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE
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Message ID 1518169550-5987-1-git-send-email-jasowang@redhat.com
State New, archived
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  • [V4,1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE
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Commit Message

Jason Wang Feb. 9, 2018, 9:45 a.m. UTC
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(+)

Comments

Michael S. Tsirkin Feb. 9, 2018, 3:39 p.m. UTC | #1
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
David Miller Feb. 9, 2018, 7:29 p.m. UTC | #2
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.
Eric Biggers Feb. 10, 2018, 7:32 p.m. UTC | #3
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
Jason Wang Feb. 11, 2018, 2:46 a.m. UTC | #4
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

Patch
diff mbox series

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);
 }