Patch "x86/signal: Fix restart_syscall number for x32 tasks" has been added to the 3.10-stable tree

This is a note to let you know that I've just added the patch titled

x86/signal: Fix restart_syscall number for x32 tasks

to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-signal-fix-restart_syscall-number-for-x32-tasks.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Dmitry V. Levin" <[email protected]>
Date: Tue, 1 Dec 2015 00:54:36 +0300
Subject: x86/signal: Fix restart_syscall number for x32 tasks

From: "Dmitry V. Levin" <[email protected]>

commit 22eab1108781eff09961ae7001704f7bd8fb1dce upstream.

When restarting a syscall with regs->ax == -ERESTART_RESTARTBLOCK, regs->ax is assigned to a restart_syscall number. For x32 tasks, this syscall number must have __X32_SYSCALL_BIT set, otherwise it will be an x86_64 syscall number instead of a valid x32 syscall number. This issue has been there since the introduction of x32.

---
 arch/x86/kernel/signal.c |   17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

@@ -686,12 +686,15 @@ handle_signal(struct ksignal *ksig, stru
 	signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
 }
 
-#ifdef CONFIG_X86_32
-#define NR_restart_syscall	__NR_restart_syscall
-#else /* !CONFIG_X86_32 */
-#define NR_restart_syscall	\
-	test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
-#endif /* CONFIG_X86_32 */
+static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
+{
+#if defined(CONFIG_X86_32) || !defined(CONFIG_X86_64)
+	return __NR_restart_syscall;
+#else /* !CONFIG_X86_32 && CONFIG_X86_64 */
+	return test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall :
+		__NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
+#endif /* CONFIG_X86_32 || !CONFIG_X86_64 */
+}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

@@ -720,7 +723,7 @@ static void do_signal(struct pt_regs *re
 			break;
 
 		case -ERESTART_RESTARTBLOCK:
-			regs->ax = NR_restart_syscall;
+			regs->ax = get_nr_restart_syscall(regs);
 			regs->ip -= 2;
 			break;
 		}

Patches currently in stable-queue which might be from [email protected] are

queue-3.10/x86-signal-fix-restart_syscall-number-for-x32-tasks.patch