Messages in this thread | | | Date | Wed, 11 Feb 2009 10:33:54 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH, for 2.6.29] ptrace: fix the usage of ptrace_fork() |
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* 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
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