The existing __strnlen_user macro simply resolved to strnlen. However, the
count returned by strnlen_user should include the NULL byte. This patch
fixes the __strnlen_user macro to include the NULL byte in the count.
Signed-off-by: Mark Salter <msalter@xxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
---
include/asm-generic/uaccess.h | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index ac68c99..9788568 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -289,9 +289,14 @@ strncpy_from_user(char *dst, const char __user *src, long count)
* Return 0 on exception, a value greater than N if too long
*/
#ifndef __strnlen_user
-#define __strnlen_user strnlen
+#define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
#endif
+/*
+ * Unlike strnlen, strnlen_user includes the nul terminator in
+ * its returned count. Callers should check for a returned value
+ * greater than N as an indication the string is too long.
+ */
static inline long strnlen_user(const char __user *src, long n)
{
if (!access_ok(VERIFY_READ, src, 1))
--
1.7.6.2
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