On Thu, Sep 05, 2019 at 01:17:38PM +0200, Rasmus Villemoes wrote:
On 05/09/2019 13.05, Christian Brauner wrote:
On Thu, Sep 05, 2019 at 06:19:22AM +1000, Aleksa Sarai wrote:
+ if (unlikely(!access_ok(dst, usize)))
+ return -EFAULT;
+
+ /* Deal with trailing bytes. */
+ if (usize < ksize) {
+ if (memchr_inv(src + size, 0, rest))
+ return -EFBIG;
+ } else if (usize > ksize) {
+ if (__memzero_user(dst + size, rest))
+ return -EFAULT;
Is zeroing that memory really our job? Seems to me we should just check
it is zeroed.
Of course it is, otherwise you'd require userspace to clear the output
buffer it gives us, which in the majority of cases is wasted work. It's
much easier to reason about if we just say "the kernel populates [uaddr,
uaddr + usize)".
I don't really mind either way so sure. :)
