[S390] uaccess: implement strict user copy checks
Same as on x86 and sparc, besides the fact that enabling the option
will just emit compile time warnings instead of errors.
Keeps allyesconfig kernels compiling.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index cbf0a87..d6b1ed0 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -265,6 +265,12 @@
return uaccess.copy_from_user(n, from, to);
}
+extern void copy_from_user_overflow(void)
+#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
+__compiletime_warning("copy_from_user() buffer size is not provably correct")
+#endif
+;
+
/**
* copy_from_user: - Copy a block of data from user space.
* @to: Destination address, in kernel space.
@@ -284,7 +290,13 @@
static inline unsigned long __must_check
copy_from_user(void *to, const void __user *from, unsigned long n)
{
+ unsigned int sz = __compiletime_object_size(to);
+
might_fault();
+ if (unlikely(sz != -1 && sz < n)) {
+ copy_from_user_overflow();
+ return n;
+ }
if (access_ok(VERIFY_READ, from, n))
n = __copy_from_user(to, from, n);
else
