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x86/signal: Fix restart_syscall number for x32 tasks

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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: Elvira Khabirova <lineprinter0@gmail.com>
Signed-off-by: Dmitry 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Dmitry V. Levin 2015-12-01 00:54:36 +03:00 committed by Thomas Gleixner
parent 8e8efe0379
commit 22eab11087
1 changed files with 10 additions and 7 deletions
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17
arch/x86/kernel/signal.c
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@ -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;
}