Re: [PATCH v2] mtd: sa1100: avoid VLA in sa1100_setup_mtd

[Boris Brezillon]

On Mon,  5 Nov 2018 08:58:35 +0100
Boris Brezillon  wrote:

> Enabling -Wvla found another variable-length array with randconfig
> testing:
> 
> drivers/mtd/maps/sa1100-flash.c: In function 'sa1100_setup_mtd':
> drivers/mtd/maps/sa1100-flash.c:224:10: error: ISO C90 forbids variable 
> length array 'cdev' [-Werror=vla]
> 
> Dynamically allocate the cdev array passed to mtd_concat_create()
> instead of using a VLA.
> 
> Reported-by: Arnd Bergmann 
> Signed-off-by: Boris Brezillon 
> Cc: Kees Cook 
> Cc: Olof Johansson 

Queued to the mtd fixes branch.

> ---
> Changes in v2:
> - Allocate cdev dynamically instead of having a fixed-size array
> 
> Hello,
> 
> I'm planning to queue this patch to the mtd/fixes PR. Arnd, Kees, feel
> free to add your R-b.
> 
> Regards,
> 
> Boris
> ---
>  drivers/mtd/maps/sa1100-flash.c | 10 +-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/maps/sa1100-flash.c b/drivers/mtd/maps/sa1100-flash.c
> index 784c6e1a0391..fd5fe12d7461 100644
> --- a/drivers/mtd/maps/sa1100-flash.c
> +++ b/drivers/mtd/maps/sa1100-flash.c
> @@ -221,7 +221,14 @@ static struct sa_info *sa1100_setup_mtd(struct 
> platform_device *pdev,
>   info->mtd = info->subdev[0].mtd;
>   ret = 0;
>   } else if (info->num_subdev > 1) {
> - struct mtd_info *cdev[nr];
> + struct mtd_info **cdev;
> +
> + cdev = kmalloc_array(nr, sizeof(*cdev), GFP_KERNEL);
> + if (!cdev) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
>   /*
>* We detected multiple devices.  Concatenate them together.
>*/
> @@ -230,6 +237,7 @@ static struct sa_info *sa1100_setup_mtd(struct 
> platform_device *pdev,
>  
>   info->mtd = mtd_concat_create(cdev, info->num_subdev,
> plat->name);
> + kfree(cdev);
>   if (info->mtd == NULL) {
>   ret = -ENXIO;
>   goto err;

Re: [PATCH v2] mtd: sa1100: avoid VLA in sa1100_setup_mtd

[Boris Brezillon]

On Mon,  5 Nov 2018 08:58:35 +0100
Boris Brezillon  wrote:

> Enabling -Wvla found another variable-length array with randconfig
> testing:
> 
> drivers/mtd/maps/sa1100-flash.c: In function 'sa1100_setup_mtd':
> drivers/mtd/maps/sa1100-flash.c:224:10: error: ISO C90 forbids variable 
> length array 'cdev' [-Werror=vla]
> 
> Dynamically allocate the cdev array passed to mtd_concat_create()
> instead of using a VLA.
> 
> Reported-by: Arnd Bergmann 
> Signed-off-by: Boris Brezillon 
> Cc: Kees Cook 
> Cc: Olof Johansson 
> ---
> Changes in v2:
> - Allocate cdev dynamically instead of having a fixed-size array
> 
> Hello,
> 
> I'm planning to queue this patch to the mtd/fixes PR. Arnd, Kees, feel

^ I meant branch,
not PR, but this patch should also be part of the 4.20-rc2 fixes PR.

> free to add your R-b.
> 
> Regards,
> 
> Boris
> ---
>  drivers/mtd/maps/sa1100-flash.c | 10 +-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/maps/sa1100-flash.c b/drivers/mtd/maps/sa1100-flash.c
> index 784c6e1a0391..fd5fe12d7461 100644
> --- a/drivers/mtd/maps/sa1100-flash.c
> +++ b/drivers/mtd/maps/sa1100-flash.c
> @@ -221,7 +221,14 @@ static struct sa_info *sa1100_setup_mtd(struct 
> platform_device *pdev,
>   info->mtd = info->subdev[0].mtd;
>   ret = 0;
>   } else if (info->num_subdev > 1) {
> - struct mtd_info *cdev[nr];
> + struct mtd_info **cdev;
> +
> + cdev = kmalloc_array(nr, sizeof(*cdev), GFP_KERNEL);
> + if (!cdev) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
>   /*
>* We detected multiple devices.  Concatenate them together.
>*/
> @@ -230,6 +237,7 @@ static struct sa_info *sa1100_setup_mtd(struct 
> platform_device *pdev,
>  
>   info->mtd = mtd_concat_create(cdev, info->num_subdev,
> plat->name);
> + kfree(cdev);
>   if (info->mtd == NULL) {
>   ret = -ENXIO;
>   goto err;

[PATCH v2] mtd: sa1100: avoid VLA in sa1100_setup_mtd

[Boris Brezillon]

Enabling -Wvla found another variable-length array with randconfig
testing:

drivers/mtd/maps/sa1100-flash.c: In function 'sa1100_setup_mtd':
drivers/mtd/maps/sa1100-flash.c:224:10: error: ISO C90 forbids variable length 
array 'cdev' [-Werror=vla]

Dynamically allocate the cdev array passed to mtd_concat_create()
instead of using a VLA.

Reported-by: Arnd Bergmann 
Signed-off-by: Boris Brezillon 
Cc: Kees Cook 
Cc: Olof Johansson 
---
Changes in v2:
- Allocate cdev dynamically instead of having a fixed-size array

Hello,

I'm planning to queue this patch to the mtd/fixes PR. Arnd, Kees, feel
free to add your R-b.

Regards,

Boris
---
 drivers/mtd/maps/sa1100-flash.c | 10 +-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/maps/sa1100-flash.c b/drivers/mtd/maps/sa1100-flash.c
index 784c6e1a0391..fd5fe12d7461 100644
--- a/drivers/mtd/maps/sa1100-flash.c
+++ b/drivers/mtd/maps/sa1100-flash.c
@@ -221,7 +221,14 @@ static struct sa_info *sa1100_setup_mtd(struct 
platform_device *pdev,
info->mtd = info->subdev[0].mtd;
ret = 0;
} else if (info->num_subdev > 1) {
-   struct mtd_info *cdev[nr];
+   struct mtd_info **cdev;
+
+   cdev = kmalloc_array(nr, sizeof(*cdev), GFP_KERNEL);
+   if (!cdev) {
+   ret = -ENOMEM;
+   goto err;
+   }
+
/*
 * We detected multiple devices.  Concatenate them together.
 */
@@ -230,6 +237,7 @@ static struct sa_info *sa1100_setup_mtd(struct 
platform_device *pdev,
 
info->mtd = mtd_concat_create(cdev, info->num_subdev,
  plat->name);
+   kfree(cdev);
if (info->mtd == NULL) {
ret = -ENXIO;
goto err;
-- 
2.17.1