Re: [PATCH] viafb: Use sizeof struct rather than pointer

Re: [PATCH] viafb: Use sizeof struct rather than pointer

[Thiago Farina]

On Sat, Nov 21, 2009 at 5:02 PM, Roel Kluin <roel.kluin@gmail.com> wrote:
> The returned error should be negative
>
Hum? This belong to this patch?

[PATCH] viafb: Use sizeof struct rather than pointer

[Roel Kluin]

The sizeof the struct should be used rather than of the pointer

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
 drivers/video/via/viafbdev.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

Unless I am mistaken?

diff --git a/drivers/video/via/viafbdev.c b/drivers/video/via/viafbdev.c
index 56ec696..6cf4cb8 100644
--- a/drivers/video/via/viafbdev.c
+++ b/drivers/video/via/viafbdev.c
@@ -680,7 +680,7 @@ static int viafb_ioctl(struct fb_info *info, u_int cmd, u_long arg)
 		if (!viafb_gamma_table)
 			return -ENOMEM;
 		if (copy_from_user(viafb_gamma_table, argp,
-				sizeof(viafb_gamma_table))) {
+				sizeof(*viafb_gamma_table))) {
 			kfree(viafb_gamma_table);
 			return -EFAULT;
 		}

Re: [PATCH] viafb: Use sizeof struct rather than pointer

[Roel Kluin]

The returned error should be negative

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
 drivers/video/via/viafbdev.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

> Unless I am mistaken?

There was another in the same file:

diff --git a/drivers/video/via/viafbdev.c b/drivers/video/via/viafbdev.c
index 56ec696..7b181e7 100644
--- a/drivers/video/via/viafbdev.c
+++ b/drivers/video/via/viafbdev.c
@@ -680,7 +680,7 @@ static int viafb_ioctl(struct fb_info *info, u_int cmd, u_long arg)
 		if (!viafb_gamma_table)
 			return -ENOMEM;
 		if (copy_from_user(viafb_gamma_table, argp,
-				sizeof(viafb_gamma_table))) {
+				sizeof(*viafb_gamma_table))) {
 			kfree(viafb_gamma_table);
 			return -EFAULT;
 		}
@@ -694,7 +694,7 @@ static int viafb_ioctl(struct fb_info *info, u_int cmd, u_long arg)
 			return -ENOMEM;
 		viafb_get_gamma_table(viafb_gamma_table);
 		if (copy_to_user(argp, viafb_gamma_table,
-			sizeof(viafb_gamma_table))) {
+			sizeof(*viafb_gamma_table))) {
 			kfree(viafb_gamma_table);
 			return -EFAULT;
 		}

Re: [Linux-fbdev-devel] [PATCH] viafb: Use sizeof struct rather than pointer

[Florian Tobias Schandinat]

Hi,

Roel Kluin schrieb:
> diff --git a/drivers/video/via/viafbdev.c b/drivers/video/via/viafbdev.c
> index 56ec696..7b181e7 100644
> --- a/drivers/video/via/viafbdev.c
> +++ b/drivers/video/via/viafbdev.c
> @@ -680,7 +680,7 @@ static int viafb_ioctl(struct fb_info *info, u_int cmd, u_long arg)
>  		if (!viafb_gamma_table)
>  			return -ENOMEM;
>  		if (copy_from_user(viafb_gamma_table, argp,
> -				sizeof(viafb_gamma_table))) {
> +				sizeof(*viafb_gamma_table))) {
>  			kfree(viafb_gamma_table);
>  			return -EFAULT;
>  		}
> @@ -694,7 +694,7 @@ static int viafb_ioctl(struct fb_info *info, u_int cmd, u_long arg)
>  			return -ENOMEM;
>  		viafb_get_gamma_table(viafb_gamma_table);
>  		if (copy_to_user(argp, viafb_gamma_table,
> -			sizeof(viafb_gamma_table))) {
> +			sizeof(*viafb_gamma_table))) {
>  			kfree(viafb_gamma_table);
>  			return -EFAULT;
>  		}

I'm sorry but I fear your fix isn't correct. The reason is a few lines 
above:

u32 *viafb_gamma_table;
...
viafb_gamma_table = kmalloc(256 * sizeof(u32), GFP_KERNEL);

so probably the right solution would look like this:

copy_from_user(viafb_gamma_table, argp, 256 * sizeof(u32))
copy_to_user(argp, viafb_gamma_table, 256 * sizeof(u32))

However viafb has way too many private ioctls. I would be curious 
whether there exists any program that uses any of them so that they 
could be tested. As this ioctl didn't work very well I vote to remove it 
at least temporarily.

Thanks for highlighting this problem,


Florian Tobias Schandinat