[PATCH 5.4 63/78] clone3: ensure copy_thread_tls is implemented

Greg Kroah-Hartman
2020-01-14T10:06:08Z

From: Amanieu d'Antras <amanieu@gmail.com>

commit dd499f7a7e34270208350a849ef103c0b3ae477f upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/fork.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2513,6 +2513,16 @@ 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 usize)