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Commit 22eab110 authored by Dmitry V. Levin's avatar Dmitry V. Levin Committed by Thomas Gleixner
Browse files

x86/signal: Fix restart_syscall number for x32 tasks 



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.

Reported-by: strace/tests/restart_syscall.test
Reported-and-tested-by: default avatarElvira Khabirova <lineprinter0@gmail.com>
Signed-off-by: default avatarDmitry V. Levin <ldv@altlinux.org>
Cc: Elvira Khabirova <lineprinter0@gmail.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20151130215436.GA25996@altlinux.org


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 8e8efe03

arch/x86/kernel/signal.c

+10 −7
Original line number Diff line number Diff line
@@ -690,12 +690,15 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs) 
	signal_setup_done(failed, ksig, stepping);

}



#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
@@ -724,7 +727,7 @@ void do_signal(struct pt_regs *regs) 
			break;



		case -ERESTART_RESTARTBLOCK:

			regs->ax = NR_restart_syscall;

			regs->ax = get_nr_restart_syscall(regs);

			regs->ip -= 2;

			break;

		}