Re: [PATCH 3.2 059/221] autofs4: check dev ioctl size before allocating

[Ian Kent]

On Tue, 2015-05-05 at 02:16 +0100, Ben Hutchings wrote:
> 3.2.69-rc1 review patch.  If anyone has any objections, please let me know.

Perhaps you should also consider including commit 0a280962 along with
this one.

> 
> ------------------
> 
> From: Sasha Levin <sasha.levin@xxxxxxxxxx>
> 
> commit e53d77eb8bb616e903e34cc7a918401bee3b5149 upstream.
> 
> There wasn't any check of the size passed from userspace before trying
> to allocate the memory required.
> 
> This meant that userspace might request more space than allowed,
> triggering an OOM.
> 
> Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
> Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> ---
>  fs/autofs4/dev-ioctl.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> --- a/fs/autofs4/dev-ioctl.c
> +++ b/fs/autofs4/dev-ioctl.c
> @@ -103,6 +103,9 @@ static struct autofs_dev_ioctl *copy_dev
>  	if (tmp.size < sizeof(tmp))
>  		return ERR_PTR(-EINVAL);
>  
> +	if (tmp.size > (PATH_MAX + sizeof(tmp)))
> +		return ERR_PTR(-ENAMETOOLONG);
> +
>  	return memdup_user(in, tmp.size);
>  }
>  
> 


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