1 files changed, 23 insertions, 6 deletions

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 3cb15ea48aee..d4dfac878fab 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -100,11 +100,12 @@ union bpf_attr;
 #define __MAP(n,...) __MAP##n(__VA_ARGS__)
 
 #define __SC_DECL(t, a)	t a
-#define __TYPE_IS_L(t)	(__same_type((t)0, 0L))
-#define __TYPE_IS_UL(t)	(__same_type((t)0, 0UL))
-#define __TYPE_IS_LL(t) (__same_type((t)0, 0LL) || __same_type((t)0, 0ULL))
+#define __TYPE_AS(t, v)	__same_type((__force t)0, v)
+#define __TYPE_IS_L(t)	(__TYPE_AS(t, 0L))
+#define __TYPE_IS_UL(t)	(__TYPE_AS(t, 0UL))
+#define __TYPE_IS_LL(t) (__TYPE_AS(t, 0LL) || __TYPE_AS(t, 0ULL))
 #define __SC_LONG(t, a) __typeof(__builtin_choose_expr(__TYPE_IS_LL(t), 0LL, 0L)) a
-#define __SC_CAST(t, a)	(t) a
+#define __SC_CAST(t, a)	(__force t) a
 #define __SC_ARGS(t, a)	a
 #define __SC_TEST(t, a) (void)BUILD_BUG_ON_ZERO(!__TYPE_IS_LL(t) && sizeof(t) > sizeof(long))
 
@@ -206,6 +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);
@@ -578,12 +595,12 @@ asmlinkage long sys_preadv(unsigned long fd, const struct iovec __user *vec,
 			   unsigned long vlen, unsigned long pos_l, unsigned long pos_h);
 asmlinkage long sys_preadv2(unsigned long fd, const struct iovec __user *vec,
 			    unsigned long vlen, unsigned long pos_l, unsigned long pos_h,
-			    int flags);
+			    rwf_t flags);
 asmlinkage long sys_pwritev(unsigned long fd, const struct iovec __user *vec,
 			    unsigned long vlen, unsigned long pos_l, unsigned long pos_h);
 asmlinkage long sys_pwritev2(unsigned long fd, const struct iovec __user *vec,
 			    unsigned long vlen, unsigned long pos_l, unsigned long pos_h,
-			    int flags);
+			    rwf_t flags);
 asmlinkage long sys_getcwd(char __user *buf, unsigned long size);
 asmlinkage long sys_mkdir(const char __user *pathname, umode_t mode);
 asmlinkage long sys_chdir(const char __user *filename);