On Tue, Apr 4, 2017 at 2:09 PM, Laura Abbott <labbott@xxxxxxxxxx> wrote:
> virt_addr_valid was previously insufficient to validate if virt_to_page
> could be called on an address on arm64. This has since been fixed up
> so there is no need for the extra check. Drop it.
>
> Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
> ---
> I've given this some testing on my machine and haven't seen any problems
> (e.g. random crashes without the check) and the fix has been in for long
> enough now. I'm in no rush to have this merged so I'm okay if this sits in
> a tree somewhere to get more testing.
Awesome, thanks! I'll get it into my usercopy branch for -next.
-Kees
> ---
> mm/usercopy.c | 11 -----------
> 1 file changed, 11 deletions(-)
>
> diff --git a/mm/usercopy.c b/mm/usercopy.c
> index d155e12563b1..4d23a0e0e232 100644
> --- a/mm/usercopy.c
> +++ b/mm/usercopy.c
> @@ -206,17 +206,6 @@ static inline const char *check_heap_object(const void *ptr, unsigned long n,
> {
> struct page *page;
>
> - /*
> - * Some architectures (arm64) return true for virt_addr_valid() on
> - * vmalloced addresses. Work around this by checking for vmalloc
> - * first.
> - *
> - * We also need to check for module addresses explicitly since we
> - * may copy static data from modules to userspace
> - */
> - if (is_vmalloc_or_module_addr(ptr))
> - return NULL;
> -
> if (!virt_addr_valid(ptr))
> return NULL;
>
> --
> 2.12.1
>
--
Kees Cook
Pixel Security
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