[PATCH] lib/dma-debug.c: fix memory leakage

[PATCH] lib/dma-debug.c: fix memory leakage

[miles.chen-NuS5LvNUpcJWk0Htik3J/w]

From: Miles Chen <miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>

Marty reported a memory leakage introduced by commit 3aaabbf1c39e
("lib/dma-debug.c: fix incorrect pfn calculation"). Fix it
by checking the virtual address before allocating the entry.

This patch also use virt_addr_valid() instead of virt_to_page()
to check if a virtual address is linear.

Reported-by: Marty Faltesek <mfaltesek-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Miles Chen <miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
---
 lib/dma-debug.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 1b34d210452c..7f5cdc1e6b29 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -1491,12 +1491,12 @@ void debug_dma_alloc_coherent(struct device *dev, size_t size,
 	if (unlikely(virt == NULL))
 		return;
 
-	entry = dma_entry_alloc();
-	if (!entry)
+	/* handle vmalloc and linear addresses */
+	if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
 		return;
 
-	/* handle vmalloc and linear addresses */
-	if (!is_vmalloc_addr(virt) && !virt_to_page(virt))
+	entry = dma_entry_alloc();
+	if (!entry)
 		return;
 
 	entry->type      = dma_debug_coherent;
@@ -1528,7 +1528,7 @@ void debug_dma_free_coherent(struct device *dev, size_t size,
 	};
 
 	/* handle vmalloc and linear addresses */
-	if (!is_vmalloc_addr(virt) && !virt_to_page(virt))
+	if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
 		return;
 
 	if (is_vmalloc_addr(virt))
-- 
2.12.5

Re: [PATCH] lib/dma-debug.c: fix memory leakage

[Robin Murphy]

On 22/02/18 11:22, miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org wrote:
> From: Miles Chen <miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
> 
> Marty reported a memory leakage introduced by commit 3aaabbf1c39e
> ("lib/dma-debug.c: fix incorrect pfn calculation"). Fix it
> by checking the virtual address before allocating the entry.

Oops, seems I failed to look closely enough at the surrounding diff 
context when I reviewed the original patch... :(

> This patch also use virt_addr_valid() instead of virt_to_page()
> to check if a virtual address is linear.

That's an area I happen to have been looking at lately and now 
understand a lot better, so fully agreed there as well.

Acked-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>

Maybe also worth having a proper Fixes: tag instead of just naming the 
commit in prose?

Thanks,
Robin.

> Reported-by: Marty Faltesek <mfaltesek-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Miles Chen <miles.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
> ---
>   lib/dma-debug.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index 1b34d210452c..7f5cdc1e6b29 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -1491,12 +1491,12 @@ void debug_dma_alloc_coherent(struct device *dev, size_t size,
>   	if (unlikely(virt == NULL))
>   		return;
>   
> -	entry = dma_entry_alloc();
> -	if (!entry)
> +	/* handle vmalloc and linear addresses */
> +	if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
>   		return;
>   
> -	/* handle vmalloc and linear addresses */
> -	if (!is_vmalloc_addr(virt) && !virt_to_page(virt))
> +	entry = dma_entry_alloc();
> +	if (!entry)
>   		return;
>   
>   	entry->type      = dma_debug_coherent;
> @@ -1528,7 +1528,7 @@ void debug_dma_free_coherent(struct device *dev, size_t size,
>   	};
>   
>   	/* handle vmalloc and linear addresses */
> -	if (!is_vmalloc_addr(virt) && !virt_to_page(virt))
> +	if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
>   		return;
>   
>   	if (is_vmalloc_addr(virt))
> 

Re: [PATCH] lib/dma-debug.c: fix memory leakage

[Christoph Hellwig]

Thanks, applied to the dma mapping tree for 4.16, including the Fixes
tag.