Hi,
I experienced troubles when tracing a process with strace. Sometimes,
when I killed the strace process (SIGKILL), the traced process was also
killed. I found out that it was getting SIGTRAP and, indeed, when the
traced process set up a signal handler for SIGTRAP, it no longer died.
I noticed that normally, when the traced process is continued (via
PTRACE_CONT or similar), the signal to be sent to it is stored in
current->exit_code, which is then examined by the arch-specific code and
usually leads to something like:
send_sig(current->exit_code, current, 1);
The exit_code is set in ptrace_stop(), but the tracing process may go
away while the traced process waits for it, and in that case exit_code
is left as-is. I think we must set it to zero in ptrace_untrace().
Signed-off-by: Petr Tesarik <[email protected]>
ptrace.c | 1 +
1 file changed, 1 insertion(+)
diff -pru a/kernel/ptrace.c b/kernel/ptrace.c
--- a/kernel/ptrace.c 2007-12-04 14:12:51.000000000 +0100
+++ b/kernel/ptrace.c 2007-12-04 14:13:28.000000000 +0100
@@ -52,6 +52,7 @@ void ptrace_untrace(struct task_struct *
{
spin_lock(&child->sighand->siglock);
if (child->state == TASK_TRACED) {
+ child->exit_code = 0;
if (child->signal->flags & SIGNAL_STOP_STOPPED) {
child->state = TASK_STOPPED;
} else {
--
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