From: Amanieu d'Antras <amanieu@gmail.com>
Date: Thu, 2 Jan 2020 18:24:13 +0100
Subject: clone3: ensure copy_thread_tls is implemented
Git-commit: dd499f7a7e34270208350a849ef103c0b3ae477f
Patch-mainline: v5.5-rc6
References: bsc#1163988

copy_thread implementations handle CLONE_SETTLS by reading the TLS
value from the registers containing the syscall arguments for
clone. This doesn't work with clone3 since the TLS value is passed
in clone_args instead.

Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Cc: <stable@vger.kernel.org> # 5.3.x
Link: https://lore.kernel.org/r/20200102172413.654385-8-amanieu@gmail.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
---
 kernel/fork.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2520,6 +2520,16 @@ SYSCALL_DEFINE5(clone, unsigned long, cl
 #endif
 
 #ifdef __ARCH_WANT_SYS_CLONE3
+
+/*
+ * copy_thread implementations handle CLONE_SETTLS by reading the TLS value from
+ * the registers containing the syscall arguments for clone. This doesn't work
+ * with clone3 since the TLS value is passed in clone_args instead.
+ */
+#ifndef CONFIG_HAVE_COPY_THREAD_TLS
+#error clone3 requires copy_thread_tls support in arch
+#endif
+
 noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
 					      struct clone_args __user *uargs,
 					      size_t size)