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| author | Oleg Nesterov <oleg@redhat.com> | 2009-04-02 16:58:14 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-02 19:04:59 -0700 |
| commit | 4576145c1ecdaaea9ef8976a48335206aa1ebf91 (patch) | |
| tree | b20b51848380b708f4158852b1bb4afa29ffc5f0 | |
| parent | b1b4c6799fb59e710454bfe0ab477cb8523a8667 (diff) | |
| download | op-kernel-dev-4576145c1ecdaaea9ef8976a48335206aa1ebf91.zip op-kernel-dev-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>
| -rw-r--r-- | include/linux/ptrace.h | 1 | ||||
| -rw-r--r-- | kernel/ptrace.c | 9 |
2 files changed, 8 insertions, 2 deletions
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 98b93ca..1a2b0cb 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -94,6 +94,7 @@ extern void ptrace_notify(int exit_code); extern void __ptrace_link(struct task_struct *child, struct task_struct *new_parent); extern void __ptrace_unlink(struct task_struct *child); +extern int __ptrace_detach(struct task_struct *tracer, struct task_struct *p); extern void ptrace_fork(struct task_struct *task, unsigned long clone_flags); #define PTRACE_MODE_READ 1 #define PTRACE_MODE_ATTACH 2 diff --git a/kernel/ptrace.c b/kernel/ptrace.c index f62a568..ee553b6 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; } |
