asm-generic: uaccess: add missing access_ok() check to strnlen_user()
The strnlen_user() function was missing a access_ok() check on the pointer
given. We've had cases on Blackfin systems where test programs caused
kernel crashes here because userspace passed up a NULL/-1 pointer and the
kernel gladly attempted to run strlen() on it.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index 6d8cab2..5dd511b 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -291,6 +291,8 @@
#ifndef strnlen_user
static inline long strnlen_user(const char __user *src, long n)
{
+ if (!access_ok(VERIFY_READ, src, 1))
+ return 0;
return strlen((void * __force)src) + 1;
}
#endif
