Merge branch 'x86-syscall-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[platform/kernel/linux-rpi.git] / include / linux / syscalls.h

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 138c945..d4dfac8 100644 (file)
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -207,6 +207,22 @@ extern struct trace_event_functions exit_syscall_print_funcs;
        }                                                               \
        static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 
+#ifdef TIF_FSCHECK
+/*
+ * Called before coming back to user-mode. Returning to user-mode with an
+ * address limit different than USER_DS can allow to overwrite kernel memory.
+ */
+static inline void addr_limit_user_check(void)
+{
+
+       if (!test_thread_flag(TIF_FSCHECK))
+               return;
+
+       BUG_ON(!segment_eq(get_fs(), USER_DS));
+       clear_thread_flag(TIF_FSCHECK);
+}
+#endif
+
 asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
                               qid_t id, void __user *addr);
 asmlinkage long sys_time(time_t __user *tloc);