On Thu, Apr 02, 2020 at 07:34:17AM +0000, Christophe Leroy wrote:
> [...]
> diff --git a/kernel/compat.c b/kernel/compat.c
> index 843dd17e6078..705ca7e418c6 100644
> --- a/kernel/compat.c
> +++ b/kernel/compat.c
> @@ -199,7 +199,7 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
> bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
> nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
>
> - if (!user_access_begin(umask, bitmap_size / 8))
> + if (!user_write_access_begin(umask, bitmap_size / 8))
This looks mismatched: should be user_read_access_begin()?
> return -EFAULT;
>
> while (nr_compat_longs > 1) {
> @@ -211,11 +211,11 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
> }
> if (nr_compat_longs)
> unsafe_get_user(*mask, umask++, Efault);
> - user_access_end();
> + user_read_access_end();
> return 0;
>
> Efault:
> - user_access_end();
> + user_read_access_end();
> return -EFAULT;
> }
(These correctly end read access.)
>
> @@ -228,7 +228,7 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
> bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
> nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
>
> - if (!user_access_begin(umask, bitmap_size / 8))
> + if (!user_read_access_begin(umask, bitmap_size / 8))
And ..._write_... here?
> return -EFAULT;
>
> while (nr_compat_longs > 1) {
> @@ -239,10 +239,10 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
> }
> if (nr_compat_longs)
> unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
> - user_access_end();
> + user_write_access_end();
> return 0;
> Efault:
> - user_access_end();
> + user_write_access_end();
> return -EFAULT;
> }
(These correctly end write access.)
All the others look correct. With the above fixed:
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
--
Kees Cook
