From: Mike Frysinger Date: Sun, 14 Jun 2009 06:00:02 +0000 (-0400) Subject: asm-generic: uaccess: add missing access_ok() check to strnlen_user() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9844813f226f6d07e1544e915529cb88f4fcb868;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git 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 Signed-off-by: Arnd Bergmann --- diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h index 6d8cab22e294..5dd511b62ce9 100644 --- a/include/asm-generic/uaccess.h +++ b/include/asm-generic/uaccess.h @@ -291,6 +291,8 @@ strncpy_from_user(char *dst, const char __user *src, long count) #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