Merge branch 'uaccess.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull misc uaccess updates from Al Viro:
 "Assorted uaccess patches for this cycle - the stuff that didn't fit
  into thematic series"

* 'uaccess.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  bpf: make bpf_check_uarg_tail_zero() use check_zeroed_user()
  x86: kvm_hv_set_msr(): use __put_user() instead of 32bit __clear_user()
  user_regset_copyout_zero(): use clear_user()
  TEST_ACCESS_OK _never_ had been checked anywhere
  x86: switch cp_stat64() to unsafe_put_user()
  binfmt_flat: don't use __put_user()
  binfmt_elf_fdpic: don't use __... uaccess primitives
  binfmt_elf: don't bother with __{put,copy_to}_user()
  pselect6() and friends: take handling the combined 6th/7th args into helper

1 files changed, 6 insertions, 19 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c3ae2adaeccd..9693730833d2 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -74,32 +74,19 @@ int bpf_check_uarg_tail_zero(void __user *uaddr,
 			     size_t expected_size,
 			     size_t actual_size)
 {
-	unsigned char __user *addr;
-	unsigned char __user *end;
-	unsigned char val;
-	int err;
+	unsigned char __user *addr = uaddr + expected_size;
+	int res;
 
 	if (unlikely(actual_size > PAGE_SIZE))	/* silly large */
 		return -E2BIG;
 
-	if (unlikely(!access_ok(uaddr, actual_size)))
-		return -EFAULT;
-
 	if (actual_size <= expected_size)
 		return 0;
 
-	addr = uaddr + expected_size;
-	end  = uaddr + actual_size;
-
-	for (; addr < end; addr++) {
-		err = get_user(val, addr);
-		if (err)
-			return err;
-		if (val)
-			return -E2BIG;
-	}
-
-	return 0;
+	res = check_zeroed_user(addr, actual_size - expected_size);
+	if (res < 0)
+		return res;
+	return res ? 0 : -E2BIG;
 }
 
 const struct bpf_map_ops bpf_map_offload_ops = {