This is a note to let you know that I've just added the patch titled
tracing: Fix syscall_*regfunc() vs copy_process() race
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-fix-syscall_-regfunc-vs-copy_process-race.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 4af4206be2bd1933cae20c2b6fb2058dbc887f7c Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <[email protected]>
Date: Sun, 13 Apr 2014 20:58:54 +0200
Subject: tracing: Fix syscall_*regfunc() vs copy_process() race
From: Oleg Nesterov <[email protected]>
commit 4af4206be2bd1933cae20c2b6fb2058dbc887f7c upstream.
syscall_regfunc() and syscall_unregfunc() should set/clear
TIF_SYSCALL_TRACEPOINT system-wide, but do_each_thread() can race
with copy_process() and miss the new child which was not added to
the process/thread lists yet.
Change copy_process() to update the child's TIF_SYSCALL_TRACEPOINT
under tasklist.
Link: http://lkml.kernel.org/p/[email protected]
Fixes: a871bd33a6c0 "tracing: Add syscall tracepoints"
Acked-by: Frederic Weisbecker <[email protected]>
Acked-by: Paul E. McKenney <[email protected]>
Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
include/trace/syscall.h | 15 +++++++++++++++
kernel/fork.c | 2 ++
2 files changed, 17 insertions(+)
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -4,6 +4,7 @@
#include <linux/tracepoint.h>
#include <linux/unistd.h>
#include <linux/ftrace_event.h>
+#include <linux/thread_info.h>
#include <asm/ptrace.h>
@@ -32,4 +33,18 @@ struct syscall_metadata {
struct ftrace_event_call *exit_event;
};
+#if defined(CONFIG_TRACEPOINTS) && defined(CONFIG_HAVE_SYSCALL_TRACEPOINTS)
+static inline void syscall_tracepoint_update(struct task_struct *p)
+{
+ if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
+ set_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT);
+ else
+ clear_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT);
+}
+#else
+static inline void syscall_tracepoint_update(struct task_struct *p)
+{
+}
+#endif
+
#endif /* _TRACE_SYSCALL_H */
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1484,7 +1484,9 @@ static struct task_struct *copy_process(
total_forks++;
spin_unlock(¤t->sighand->siglock);
+ syscall_tracepoint_update(p);
write_unlock_irq(&tasklist_lock);
+
proc_fork_connector(p);
cgroup_post_fork(p);
if (clone_flags & CLONE_THREAD)
Patches currently in stable-queue which might be from [email protected] are
queue-3.14/tracing-fix-syscall_-regfunc-vs-copy_process-race.patch
queue-3.14/ptrace-x86-force-iret-path-after-a-ptrace_stop.patch
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