diff mbox series

[13/21] dmaengine: stm32-mdma: Annotate struct stm32_mdma_desc with __counted_by

Message ID 20230817235859.49846-13-keescook@chromium.org (mailing list archive)
State Mainlined
Commit 035472170a2a21fc62d8258883a9f566943058b7
Headers show
Series dmaengine: Annotate with __counted_by | expand

Commit Message

Kees Cook Aug. 17, 2023, 11:58 p.m. UTC
Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct stm32_mdma_desc.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Vinod Koul <vkoul@kernel.org>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: dmaengine@vger.kernel.org
Cc: linux-stm32@st-md-mailman.stormreply.com
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/dma/stm32-mdma.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Comments

Gustavo A. R. Silva Aug. 18, 2023, 1:25 a.m. UTC | #1
On 8/17/23 17:58, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct stm32_mdma_desc.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Vinod Koul <vkoul@kernel.org>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
> Cc: dmaengine@vger.kernel.org
> Cc: linux-stm32@st-md-mailman.stormreply.com
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

> ---
>   drivers/dma/stm32-mdma.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
> index 0de234022c6d..926d6ecf1274 100644
> --- a/drivers/dma/stm32-mdma.c
> +++ b/drivers/dma/stm32-mdma.c
> @@ -224,7 +224,7 @@ struct stm32_mdma_desc {
>   	u32 ccr;
>   	bool cyclic;
>   	u32 count;
> -	struct stm32_mdma_desc_node node[];
> +	struct stm32_mdma_desc_node node[] __counted_by(count);
>   };
>   
>   struct stm32_mdma_dma_config {
> @@ -321,6 +321,7 @@ static struct stm32_mdma_desc *stm32_mdma_alloc_desc(
>   	desc = kzalloc(struct_size(desc, node, count), GFP_NOWAIT);
>   	if (!desc)
>   		return NULL;
> +	desc->count = count;
>   
>   	for (i = 0; i < count; i++) {
>   		desc->node[i].hwdesc =
> @@ -330,8 +331,6 @@ static struct stm32_mdma_desc *stm32_mdma_alloc_desc(
>   			goto err;
>   	}
>   
> -	desc->count = count;
> -
>   	return desc;
>   
>   err:
diff mbox series

Patch

diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
index 0de234022c6d..926d6ecf1274 100644
--- a/drivers/dma/stm32-mdma.c
+++ b/drivers/dma/stm32-mdma.c
@@ -224,7 +224,7 @@  struct stm32_mdma_desc {
 	u32 ccr;
 	bool cyclic;
 	u32 count;
-	struct stm32_mdma_desc_node node[];
+	struct stm32_mdma_desc_node node[] __counted_by(count);
 };
 
 struct stm32_mdma_dma_config {
@@ -321,6 +321,7 @@  static struct stm32_mdma_desc *stm32_mdma_alloc_desc(
 	desc = kzalloc(struct_size(desc, node, count), GFP_NOWAIT);
 	if (!desc)
 		return NULL;
+	desc->count = count;
 
 	for (i = 0; i < count; i++) {
 		desc->node[i].hwdesc =
@@ -330,8 +331,6 @@  static struct stm32_mdma_desc *stm32_mdma_alloc_desc(
 			goto err;
 	}
 
-	desc->count = count;
-
 	return desc;
 
 err: