X-Git-Url: http://git.cascardo.eti.br/?a=blobdiff_plain;f=arch%2Farm64%2Finclude%2Fasm%2Fuaccess.h;h=55d0adbf65098a78241d45038d1a57f642a7992e;hb=b5cd891716a9ef118ce8d3a367b6b0fa912447fc;hp=c47257c91b77e3d6516000c0c8bec5705b97b6dc;hpb=b304746c2a71fb0c001b5db93ea677d32f95b95f;p=cascardo%2Flinux.git

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index c47257c91b77..55d0adbf6509 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -21,6 +21,7 @@
 /*
  * User space memory access functions
  */
+#include <linux/bitops.h>
 #include <linux/kasan-checks.h>
 #include <linux/string.h>
 #include <linux/thread_info.h>
@@ -102,6 +103,13 @@ static inline void set_fs(mm_segment_t fs)
 	flag;								\
 })
 
+/*
+ * When dealing with data aborts or instruction traps we may end up with
+ * a tagged userland pointer. Clear the tag to get a sane pointer to pass
+ * on to access_ok(), for instance.
+ */
+#define untagged_addr(addr)		sign_extend64(addr, 55)
+
 #define access_ok(type, addr, size)	__range_ok(addr, size)
 #define user_addr_max			get_fs
 
@@ -278,14 +286,16 @@ static inline unsigned long __must_check __copy_to_user(void __user *to, const v
 
 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 {
+	unsigned long res = n;
 	kasan_check_write(to, n);
 
 	if (access_ok(VERIFY_READ, from, n)) {
 		check_object_size(to, n, false);
-		n = __arch_copy_from_user(to, from, n);
-	} else /* security hole - plug it */
-		memset(to, 0, n);
-	return n;
+		res = __arch_copy_from_user(to, from, n);
+	}
+	if (unlikely(res))
+		memset(to + (n - res), 0, res);
+	return res;
 }
 
 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)