parisc: add strict copy size checks (v2)

Add CONFIG_DEBUG_STRICT_USER_COPY_CHECKS, copied from the x86
implementation. Tested with 32 and 64bit kernel.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

1 files changed, 25 insertions, 2 deletions

diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index 7cf799d70b4..ff4cf9dab8d 100644
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -7,6 +7,7 @@
 #include <asm/page.h>
 #include <asm/system.h>
 #include <asm/cache.h>
+#include <asm/errno.h>
 #include <asm-generic/uaccess-unaligned.h>
 
 #define VERIFY_READ 0
@@ -234,13 +235,35 @@ extern long lstrnlen_user(const char __user *,long);
 
 unsigned long copy_to_user(void __user *dst, const void *src, unsigned long len);
 #define __copy_to_user copy_to_user
-unsigned long copy_from_user(void *dst, const void __user *src, unsigned long len);
-#define __copy_from_user copy_from_user
+unsigned long __copy_from_user(void *dst, const void __user *src, unsigned long len);
 unsigned long copy_in_user(void __user *dst, const void __user *src, unsigned long len);
 #define __copy_in_user copy_in_user
 #define __copy_to_user_inatomic __copy_to_user
 #define __copy_from_user_inatomic __copy_from_user
 
+extern void copy_from_user_overflow(void)
+#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
+        __compiletime_error("copy_from_user() buffer size is not provably correct")
+#else
+        __compiletime_warning("copy_from_user() buffer size is not provably correct")
+#endif
+;
+
+static inline unsigned long __must_check copy_from_user(void *to,
+                                          const void __user *from,
+                                          unsigned long n)
+{
+        int sz = __compiletime_object_size(to);
+        int ret = -EFAULT;
+
+        if (likely(sz == -1 || !__builtin_constant_p(n) || sz >= n))
+                ret = __copy_from_user(to, from, n);
+        else
+                copy_from_user_overflow();
+
+        return ret;
+}
+
 struct pt_regs;
 int fixup_exception(struct pt_regs *regs);