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authorOleg Nesterov <oleg@redhat.com>2009-04-02 16:58:14 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-02 19:04:59 -0700
commit4576145c1ecdaaea9ef8976a48335206aa1ebf91 (patch)
treeb20b51848380b708f4158852b1bb4afa29ffc5f0 /kernel/ptrace.c
parentb1b4c6799fb59e710454bfe0ab477cb8523a8667 (diff)
downloadlinux-2.6.34-ux500-4576145c1ecdaaea9ef8976a48335206aa1ebf91.tar.gz
ptrace: fix possible zombie leak on PTRACE_DETACH
When ptrace_detach() takes tasklist, the tracee can be SIGKILL'ed. If it has already passed exit_notify() we can leak a zombie, because a) ptracing disables the auto-reaping logic, and b) ->real_parent was not notified about the child's death. ptrace_detach() should follow the ptrace_exit's logic, change the code accordingly. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Roland McGrath <roland@redhat.com> Tested-by: Denys Vlasenko <dvlasenk@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/ptrace.c')
-rw-r--r--kernel/ptrace.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index f62a568e84e..ee553b6ad12 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -237,6 +237,8 @@ out:
int ptrace_detach(struct task_struct *child, unsigned int data)
{
+ int dead = 0;
+
if (!valid_signal(data))
return -EIO;
@@ -244,18 +246,21 @@ int ptrace_detach(struct task_struct *child, unsigned int data)
ptrace_disable(child);
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
- /* protect against de_thread()->release_task() */
write_lock_irq(&tasklist_lock);
+ /* protect against de_thread()->release_task() */
if (child->ptrace) {
child->exit_code = data;
- __ptrace_unlink(child);
+ dead = __ptrace_detach(current, child);
if (!child->exit_state)
wake_up_process(child);
}
write_unlock_irq(&tasklist_lock);
+ if (unlikely(dead))
+ release_task(child);
+
return 0;
}