The patch titled ptrace: use safer wake up on ptrace_detach() has been removed from the -mm tree. Its filename was ptrace-use-safer-wake-up-on-ptrace_detach.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: ptrace: use safer wake up on ptrace_detach() From: Tejun Heo <tj@xxxxxxxxxx> The wake_up_process() call in ptrace_detach() is spurious and not interlocked with the tracee state. IOW, the tracee could be running or sleeping in any place in the kernel by the time wake_up_process() is called. This can lead to the tracee waking up unexpectedly which can be dangerous. The wake_up is spurious and should be removed but for now reduce its toxicity by only waking up if the tracee is in TRACED or STOPPED state. This bug can possibly be used as an attack vector. I don't think it will take too much effort to come up with an attack which triggers oops somewhere. Most sleeps are wrapped in condition test loops and should be safe but we have quite a number of places where sleep and wakeup conditions are expected to be interlocked. Although the window of opportunity is tiny, ptrace can be used by non-privileged users and with some loading the window can definitely be extended and exploited. Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> Acked-by: Roland McGrath <roland@xxxxxxxxxx> Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: <stable@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/ptrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN kernel/ptrace.c~ptrace-use-safer-wake-up-on-ptrace_detach kernel/ptrace.c --- a/kernel/ptrace.c~ptrace-use-safer-wake-up-on-ptrace_detach +++ a/kernel/ptrace.c @@ -313,7 +313,7 @@ int ptrace_detach(struct task_struct *ch child->exit_code = data; dead = __ptrace_detach(current, child); if (!child->exit_state) - wake_up_process(child); + wake_up_state(child, TASK_TRACED | TASK_STOPPED); } write_unlock_irq(&tasklist_lock); _ Patches currently in -mm which might be from tj@xxxxxxxxxx are origin.patch linux-next.patch mm-numa-aware-alloc_task_struct_node.patch mm-numa-aware-alloc_thread_info_node.patch kthread-numa-aware-kthread_create_on_cpu.patch kthread-use-kthread_create_on_cpu.patch smp-move-smp-setup-functions-to-kernel-smpc.patch scatterlist-new-helper-functions.patch fs-devpts_pty_new-return-enomem-if-dentry-allocation-failed.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html