3.16.7-ckt14 -stable review patch. If anyone has any objections, please let me
know.
------------------
From: Jan Kara <j...@suse.cz>
commit f18c34e483ff6b1d9866472221e4015b3a4698e4 upstream.
If the specified maximum length of the string is a multiple of unsigned
long, we would load one long behind the specified maximum. If that
happens to be in a next page, we can hit a page fault although we were
not expected to.
Fix the off-by-one bug in the test whether we are at the end of the
specified range.
Signed-off-by: Jan Kara <j...@suse.cz>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriq...@canonical.com>
---
lib/strnlen_user.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
index a28df5206d95..11649615c505 100644
--- a/lib/strnlen_user.c
+++ b/lib/strnlen_user.c
@@ -57,7 +57,8 @@ static inline long do_strnlen_user(const char __user *src,
unsigned long count,
return res + find_zero(data) + 1 - align;
}
res += sizeof(unsigned long);
- if (unlikely(max < sizeof(unsigned long)))
+ /* We already handled 'unsigned long' bytes. Did we do it all ?
*/
+ if (unlikely(max <= sizeof(unsigned long)))
break;
max -= sizeof(unsigned long);
if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
--
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