diff options
authorMike Frysinger <>2009-06-14 02:00:02 -0400
committerArnd Bergmann <>2009-06-19 14:58:07 +0200
commit9844813f226f6d07e1544e915529cb88f4fcb868 (patch)
parent0732f87761dbe417cb6e084b712d07e879e876ef (diff)
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 <>
1 files changed, 2 insertions, 0 deletions
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;