Messages in this thread Patch in this message | | | Date | Tue, 09 Jun 2009 02:39:54 -0700 | From | Greg KH <> | Subject | [patch 66/87] ptrace: fix possible zombie leak on PTRACE_DETACH |
| |
2.6.29-stable review patch. If anyone has any objections, please let us know.
------------------
From: Oleg Nesterov <oleg@redhat.com>
commit 4576145c1ecdaaea9ef8976a48335206aa1ebf91 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- include/linux/ptrace.h | 1 + kernel/ptrace.c | 9 +++++++-- 2 files changed, 8 insertions(+), 2 deletions(-)
--- 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 --- 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 *ch 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; }
| |