linux-kernel - [PATCH 5.4 63/78] clone3: ensure copy_thread

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Date:   Tue, 14 Jan 2020 11:01:37 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Amanieu dAntras <amanieu@...il.com>,
        Christian Brauner <christian.brauner@...ntu.com>
Subject: [PATCH 5.4 63/78] clone3: ensure copy_thread_tls is implemented

From: Amanieu d'Antras <amanieu@...il.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@...il.com>
Cc: <stable@...r.kernel.org> # 5.3.x
Link: https://lore.kernel.org/r/20200102172413.654385-8-amanieu@gmail.com
Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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)