* [PATCH for 3.1] ptrace: PTRACE_LISTEN forgets to unlock ->siglock
@ 2011-09-25 17:46 Oleg Nesterov
2011-09-26 8:09 ` Matt Fleming
0 siblings, 1 reply; 2+ messages in thread
From: Oleg Nesterov @ 2011-09-25 17:46 UTC (permalink / raw)
To: Linus Torvalds; +Cc: Matt Fleming, Tejun Heo, linux-kernel
If PTRACE_LISTEN fails after lock_task_sighand() it doesn't drop ->siglock.
Reported-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/ptrace.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
--- 3.1/kernel/ptrace.c~1_PTRACE_LISTEN_siglock 2011-09-25 19:14:32.000000000 +0200
+++ 3.1/kernel/ptrace.c 2011-09-25 19:40:57.000000000 +0200
@@ -744,20 +744,17 @@ int ptrace_request(struct task_struct *c
break;
si = child->last_siginfo;
- if (unlikely(!si || si->si_code >> 8 != PTRACE_EVENT_STOP))
- break;
-
- child->jobctl |= JOBCTL_LISTENING;
-
- /*
- * If NOTIFY is set, it means event happened between start
- * of this trap and now. Trigger re-trap immediately.
- */
- if (child->jobctl & JOBCTL_TRAP_NOTIFY)
- signal_wake_up(child, true);
-
+ if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
+ child->jobctl |= JOBCTL_LISTENING;
+ /*
+ * If NOTIFY is set, it means event happened between
+ * start of this trap and now. Trigger re-trap.
+ */
+ if (child->jobctl & JOBCTL_TRAP_NOTIFY)
+ signal_wake_up(child, true);
+ ret = 0;
+ }
unlock_task_sighand(child, &flags);
- ret = 0;
break;
case PTRACE_DETACH: /* detach a process that was attached. */
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH for 3.1] ptrace: PTRACE_LISTEN forgets to unlock ->siglock
2011-09-25 17:46 [PATCH for 3.1] ptrace: PTRACE_LISTEN forgets to unlock ->siglock Oleg Nesterov
@ 2011-09-26 8:09 ` Matt Fleming
0 siblings, 0 replies; 2+ messages in thread
From: Matt Fleming @ 2011-09-26 8:09 UTC (permalink / raw)
To: Oleg Nesterov; +Cc: Linus Torvalds, Tejun Heo, linux-kernel
On Sun, 2011-09-25 at 19:46 +0200, Oleg Nesterov wrote:
> If PTRACE_LISTEN fails after lock_task_sighand() it doesn't drop ->siglock.
>
> Reported-by: Matt Fleming <matt.fleming@intel.com>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> ---
>
> kernel/ptrace.c | 23 ++++++++++-------------
> 1 file changed, 10 insertions(+), 13 deletions(-)
>
> --- 3.1/kernel/ptrace.c~1_PTRACE_LISTEN_siglock 2011-09-25 19:14:32.000000000 +0200
> +++ 3.1/kernel/ptrace.c 2011-09-25 19:40:57.000000000 +0200
> @@ -744,20 +744,17 @@ int ptrace_request(struct task_struct *c
> break;
>
> si = child->last_siginfo;
> - if (unlikely(!si || si->si_code >> 8 != PTRACE_EVENT_STOP))
> - break;
> -
> - child->jobctl |= JOBCTL_LISTENING;
> -
> - /*
> - * If NOTIFY is set, it means event happened between start
> - * of this trap and now. Trigger re-trap immediately.
> - */
> - if (child->jobctl & JOBCTL_TRAP_NOTIFY)
> - signal_wake_up(child, true);
> -
> + if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
> + child->jobctl |= JOBCTL_LISTENING;
> + /*
> + * If NOTIFY is set, it means event happened between
> + * start of this trap and now. Trigger re-trap.
> + */
> + if (child->jobctl & JOBCTL_TRAP_NOTIFY)
> + signal_wake_up(child, true);
> + ret = 0;
> + }
> unlock_task_sighand(child, &flags);
> - ret = 0;
> break;
>
> case PTRACE_DETACH: /* detach a process that was attached. */
>
Thanks Oleg, looks good to me.
--
Matt Fleming, Intel Open Source Technology Center
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