lkml.org 
[lkml]   [2009]   [Feb]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH, for 2.6.29] ptrace: fix the usage of ptrace_fork()

* Oleg Nesterov <oleg@redhat.com> wrote:

> I noticed by pure accident we have ptrace_fork() and friends. This was
> added by "x86, bts: add fork and exit handling", commit
> bf53de907dfdaac178c92d774aae7370d7b97d20
>
> I can't test this, ds_request_bts() returns -EOPNOTSUPP, but I strongly
> believe this needs the fix. I think something like this program
>
> int main(void)
> {
> int pid = fork();
>
> if (!pid) {
> ptrace(PTRACE_TRACEME, 0, NULL, NULL);
> kill(getpid(), SIGSTOP);
> fork();
> } else {
> struct ptrace_bts_config bts = {
> .flags = PTRACE_BTS_O_ALLOC,
> .size = 4 * 4096,
> };
>
> wait(NULL);
>
> ptrace(PTRACE_SETOPTIONS, pid, NULL, PTRACE_O_TRACEFORK);
> ptrace(PTRACE_BTS_CONFIG, pid, &bts, sizeof(bts));
> ptrace(PTRACE_CONT, pid, NULL, NULL);
>
> sleep(1);
> }
>
> return 0;
> }
>
> should crash the kernel.
>
> If the task is traced by its natural parent ptrace_reparented() returns 0
> but we should clear ->btsxxx anyway.
>
> This is a minimal fix for 2.6.29, we need further cleanups imho.

I've applied this fix to tip:x86/urgent for now, until the other fix
from Markus gets finalized.

Ingo


\
 
 \ /
  Last update: 2009-02-11 10:37    [W:0.107 / U:0.584 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site