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authorOleg Nesterov <oleg@redhat.com>2009-06-04 19:29:07 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-04 21:07:40 -0400
commit087eb437051b3de817720f9c80c440fc9e7dcce8 (patch)
tree25a72acabe05c3e72dddd942855d4245dfae4b82 /kernel/fork.c
parentb87297fb405ef13cac375f202d114323b076a56d (diff)
ptrace: tracehook_report_clone: fix false positives
The "trace || CLONE_PTRACE" check in tracehook_report_clone() is not right, - If the untraced task does clone(CLONE_PTRACE) the new child is not traced, we must not queue SIGSTOP. - If we forked the traced task, but the tracer exits and untraces both the forking task and the new child (after copy_process() drops tasklist_lock), we should not queue SIGSTOP too. Change the code to check task_ptrace() != 0 instead. This is still racy, but the race is harmless. We can race with another tracer attaching to this child, or the tracer can exit and detach in parallel. But giwen that we didn't do wake_up_new_task() yet, the child must have the pending SIGSTOP anyway. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Roland McGrath <roland@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index b9e2edd00726..875ffbdd96d0 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1409,7 +1409,7 @@ long do_fork(unsigned long clone_flags,
1409 } 1409 }
1410 1410
1411 audit_finish_fork(p); 1411 audit_finish_fork(p);
1412 tracehook_report_clone(trace, regs, clone_flags, nr, p); 1412 tracehook_report_clone(regs, clone_flags, nr, p);
1413 1413
1414 /* 1414 /*
1415 * We set PF_STARTING at creation in case tracing wants to 1415 * We set PF_STARTING at creation in case tracing wants to