[Precise][SRU] ptrace: renumber PTRACE_EVENT_STOP so that future new options and events can match

[Kees Cook]

BugLink: http://bugs.launchpad.net/bugs/1326905

commit 5cdf389aee90109e2e3d88085dea4dd5508a3be7 upstream.

PTRACE_EVENT_foo and PTRACE_O_TRACEfoo used to match.

New PTRACE_EVENT_STOP is the first event which has no corresponding
PTRACE_O_TRACE option.  If we will ever want to add another such option,
its PTRACE_EVENT's value will collide with PTRACE_EVENT_STOP's value.

This patch changes PTRACE_EVENT_STOP value to prevent this.

While at it, added a comment - the one atop PTRACE_EVENT block, saying
"Wait extended result codes for the above trace options", is not true
for PTRACE_EVENT_STOP.

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
Cc: Tejun Heo <tj at kernel.org>
Reviewed-by: Oleg Nesterov <oleg at redhat.com>
Cc: Pedro Alves <palves at redhat.com>
Cc: Jan Kratochvil <jan.kratochvil at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>

[kees:adjusted PTRACE_EVENT_SECCOMP as well]
Signed-off-by: Kees Cook <kees at ubuntu.com>
---
 include/linux/ptrace.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 6c50571..8f17a17 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -73,8 +73,10 @@
 #define PTRACE_EVENT_EXEC	4
 #define PTRACE_EVENT_VFORK_DONE	5
 #define PTRACE_EVENT_EXIT	6
-#define PTRACE_EVENT_STOP	7
-#define PTRACE_EVENT_SECCOMP	8
+#define PTRACE_EVENT_SECCOMP	7
+
+/* Extended result codes which enabled by means other than options.  */
+#define PTRACE_EVENT_STOP	128
 
 #include <asm/ptrace.h>
 
-- 
1.9.1


-- 
Kees Cook