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-rw-r--r--arch/x86/include/asm/uaccess_64.h2
-rw-r--r--arch/x86/lib/usercopy_64.c15
2 files changed, 8 insertions, 9 deletions
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 12a26b979bf1..f2f9b39b274a 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -231,6 +231,6 @@ __copy_from_user_inatomic_nocache(void *dst, const void __user *src,
}
unsigned long
-copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest);
+copy_user_handle_tail(char *to, char *from, unsigned len);
#endif /* _ASM_X86_UACCESS_64_H */
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index c905e89e19fe..1f33b3d1fd68 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -69,21 +69,20 @@ EXPORT_SYMBOL(copy_in_user);
* it is not necessary to optimize tail handling.
*/
__visible unsigned long
-copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest)
+copy_user_handle_tail(char *to, char *from, unsigned len)
{
- char c;
- unsigned zero_len;
-
for (; len; --len, to++) {
+ char c;
+
if (__get_user_nocheck(c, from++, sizeof(char)))
break;
if (__put_user_nocheck(c, to, sizeof(char)))
break;
}
-
- for (c = 0, zero_len = len; zerorest && zero_len; --zero_len)
- if (__put_user_nocheck(c, to++, sizeof(char)))
- break;
clac();
+
+ /* If the destination is a kernel buffer, we always clear the end */
+ if ((unsigned long)to >= TASK_SIZE_MAX)
+ memset(to, 0, len);
return len;
}