Commit-ID:  64038f292a1b33c7d46bd11f62f7798101152c00
Gitweb:     http://git.kernel.org/tip/64038f292a1b33c7d46bd11f62f7798101152c00
Author:     Oleg Nesterov <[email protected]>
AuthorDate: Sun, 15 Nov 2015 20:33:11 +0100
Committer:  Ingo Molnar <[email protected]>
CommitDate: Mon, 23 Nov 2015 09:48:17 +0100

stop_machine: Fix possible cpu_stopper_thread() crash

stop_one_cpu_nowait(fn) will crash the kernel if the callback returns
nonzero, work->done == NULL in this case.

This needs more cleanups, cpu_stop_signal_done() is called right after
we check done != NULL and it does the same check.

Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Milos Vyletel <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 kernel/stop_machine.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 867bc20..1a66a95 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -454,7 +454,7 @@ repeat:
                preempt_disable();
 
                ret = fn(arg);
-               if (ret)
+               if (ret && done)
                        done->ret = ret;
 
                /* restore preemption and check it's still balanced */
--
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