Re: [patch] agp: potential info leak in compat_agpioc_info_wrap()

Eric Dumazet
2011-09-23T07:04:23Z

Le vendredi 23 septembre 2011 à 09:19 +0300, Dan Carpenter a écrit :
> Smatch has a new check for Rosenberg type information leaks where
> structs are copied to the user with uninitialized stack data in them.
>

Hmm, automatic tools should not send patches without human check.

> The agp_info32 struct has a 4 byte hole in it so we need to clear
> that before copying it to userspace.
>
> struct agp_info32 {
> struct agp_version version; /* 0 0 */
>
> /* XXX 4 bytes hole, try to pack */
>

This makes no sense :

Why should we have a 32bit hole before an u32 field ?

Which arch mandates this ?

> u32 bridge_id; /* 4 4 */
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> diff --git a/drivers/char/agp/compat_ioctl.c b/drivers/char/agp/compat_ioctl.c
> index a48e05b..0509497 100644
> --- a/drivers/char/agp/compat_ioctl.c
> +++ b/drivers/char/agp/compat_ioctl.c
> @@ -42,6 +42,8 @@ static int compat_agpioc_info_wrap(struct agp_file_private *priv, void __user *a
>
> agp_copy_info(agp_bridge, &kerninfo);
>
> + memset(&userinfo, 0, sizeof(userinfo));
> +
> userinfo.version.major = kerninfo.version.major;
> userinfo.version.minor = kerninfo.version.minor;
> userinfo.bridge_id = kerninfo.device->vendor |