diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2011-07-08 19:14:17 +0200 |
|---|---|---|
| committer | Oleg Nesterov <oleg@redhat.com> | 2011-07-17 20:23:52 +0200 |
| commit | d184d6eb1dc3c9869e25a8e422be5c55ab0db4ac (patch) | |
| tree | efb6fbc6339ba1ce3905e3343299a4d5141da3c6 | |
| parent | dcace06cc29df927a74a6bc0e57b9bef87704377 (diff) | |
ptrace: dont send SIGSTOP on auto-attach if PT_SEIZED
The fake SIGSTOP during attach has numerous problems. PTRACE_SEIZE
is already fine, but we have basically the same problems is SIGSTOP
is sent on auto-attach, the tracer can't know if this signal signal
should be cancelled or not.
Change ptrace_event() to set JOBCTL_TRAP_STOP if the new child is
PT_SEIZED, this triggers the PTRACE_EVENT_STOP report.
Thereafter a PT_SEIZED task can never report the bogus SIGSTOP.
Test-case:
#define PTRACE_SEIZE 0x4206
#define PTRACE_SEIZE_DEVEL 0x80000000
#define PTRACE_EVENT_STOP 7
#define WEVENT(s) ((s & 0xFF0000) >> 16)
int main(void)
{
int child, grand_child, status;
long message;
child = fork();
if (!child) {
kill(getpid(), SIGSTOP);
fork();
assert(0);
return 0x23;
}
assert(ptrace(PTRACE_SEIZE, child, 0,PTRACE_SEIZE_DEVEL) == 0);
assert(wait(&status) == child);
assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
assert(ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACEFORK) == 0);
assert(ptrace(PTRACE_CONT, child, 0,0) == 0);
assert(waitpid(child, &status, 0) == child);
assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP);
assert(WEVENT(status) == PTRACE_EVENT_FORK);
assert(ptrace(PTRACE_GETEVENTMSG, child, 0, &message) == 0);
grand_child = message;
assert(waitpid(grand_child, &status, 0) == grand_child);
assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP);
assert(WEVENT(status) == PTRACE_EVENT_STOP);
kill(child, SIGKILL);
kill(grand_child, SIGKILL);
return 0;
}
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | include/linux/ptrace.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 9b5d2c901d06..800f113bea66 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -228,7 +228,11 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) child->ptrace = current->ptrace; __ptrace_link(child, current->parent); - sigaddset(&child->pending.signal, SIGSTOP); + if (child->ptrace & PT_SEIZED) + task_set_jobctl_pending(child, JOBCTL_TRAP_STOP); + else + sigaddset(&child->pending.signal, SIGSTOP); + set_tsk_thread_flag(child, TIF_SIGPENDING); } } |