lkml.org 
[lkml]   [2016]   [Nov]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] dma-debug: Avoid NULL dereference when checking sync
On Mon, 31 Oct 2016 16:11:41 +0100 Maarten ter Huurne <maarten@treewalker.org> wrote:

> check_sync() calls bucket_find_contain(), which in turn calls
> dma_get_max_seg_size(), which dereferences the device pointer.
>
> ...
>
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -1223,6 +1223,11 @@ static void check_sync(struct device *dev,
> struct hash_bucket *bucket;
> unsigned long flags;
>
> + if (!ref->dev) {
> + err_printk(dev, NULL, "DMA-API: device driver passes NULL for device to DMA sync function; cannot check usage\n");
> + return;
> + }
> +
> bucket = get_hash_bucket(ref, &flags);
>
> entry = bucket_find_contain(&bucket, ref, &flags);

Well.

a) who is calling check_sync() without having filled in ref.dev?
How does this occur? Is this a bug in the caller?

b) why does check_sync() have a `dev' argument anyway? Is there any
situation in which that will differ from ref.dev?

\
 
 \ /
  Last update: 2016-11-08 01:39    [W:0.029 / U:0.692 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site