/dev/zero: avoid repeated access_ok() checks

In read_zero, we check for access_ok() once for the count bytes.  It is
unnecessarily checked again in clear_user.  Use __clear_user, which does
not check for access_ok().

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 0aede1d6a9e..6c8b65d069e 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -690,7 +690,7 @@ static ssize_t read_zero(struct file * file, char __user * buf,
 
                 if (chunk > PAGE_SIZE)
                         chunk = PAGE_SIZE;      /* Just for latency reasons */
-                unwritten = clear_user(buf, chunk);
+                unwritten = __clear_user(buf, chunk);
                 written += chunk - unwritten;
                 if (unwritten)
                         break;