From 9dd861d55b01f1d0848f82007e8665371ae18710 Mon Sep 17 00:00:00 2001
From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Thu, 5 Nov 2015 18:50:11 -0800
Subject: mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe

As far as I can tell, strncpy_from_unsafe never returns -EFAULT.  ret is
the result of a __copy_from_user_inatomic(), which is 0 for success and
positive (in this case necessarily 1) for access error - it is never
negative.  So we were always returning the length of the, possibly
truncated, destination string.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/maccess.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'mm')

diff --git a/mm/maccess.c b/mm/maccess.c
index 1b13638d238d..d159b1c96e48 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -104,5 +104,5 @@ long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
 	pagefault_enable();
 	set_fs(old_fs);
 
-	return ret < 0 ? ret : src - unsafe_addr;
+	return ret ? -EFAULT : src - unsafe_addr;
 }
-- 
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