ptrace: don't send SIGTRAP on exec if SEIZED

ptrace_event(PTRACE_EVENT_EXEC) sends SIGTRAP if PT_TRACE_EXEC is not
set.  This is because this SIGTRAP predates PTRACE_O_TRACEEXEC option,
we do not need/want this with PT_SEIZED which can set the options during
attach.

Suggested-by: Pedro Alves <palves@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Chris Evans <scarybeasts@gmail.com>
Cc: Indan Zupancic <indan@nul.nu>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Pedro Alves <palves@redhat.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index c2f1f6a5fcb8..6fdb196caa3e 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -199,9 +199,10 @@ static inline void ptrace_event(int event, unsigned long message)
         if (unlikely(ptrace_event_enabled(current, event))) {
                 current->ptrace_message = message;
                 ptrace_notify((event << 8) | SIGTRAP);
-        } else if (event == PTRACE_EVENT_EXEC && unlikely(current->ptrace)) {
+        } else if (event == PTRACE_EVENT_EXEC) {
                 /* legacy EXEC report via SIGTRAP */
-                send_sig(SIGTRAP, current, 0);
+                if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
+                        send_sig(SIGTRAP, current, 0);
         }
 }