| Date | Wed, 05 Jan 2011 16:23:12 -0800 | From | Greg KH <> | Subject | [093/152] md: protect against NULL reference when waiting to start a raid10. |
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2.6.36-stable review patch. If anyone has any objections, please let us know.
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From: NeilBrown <neilb@suse.de>
commit 589a594be1fb8815b3f18e517be696c48664f728 upstream.
When we fail to start a raid10 for some reason, we call md_unregister_thread to kill the thread that was created.
Unfortunately md_thread() will then make one call into the handler (raid10d) even though md_wakeup_thread has not been called. This is not safe and as md_unregister_thread is called after mddev->private has been set to NULL, it will definitely cause a NULL dereference.
So fix this at both ends: - md_thread should only call the handler if THREAD_WAKEUP has been set. - raid10 should call md_unregister_thread before setting things to NULL just like all the other raid modules do.
This is applicable to 2.6.35 and later.
Reported-by: "Citizen" <citizen_lee@thecus.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/md/md.c | 5 ++--- drivers/md/raid10.c | 2 +- 2 files changed, 3 insertions(+), 4 deletions(-)
--- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -6040,9 +6040,8 @@ static int md_thread(void * arg) || kthread_should_stop(), thread->timeout); - clear_bit(THREAD_WAKEUP, &thread->flags); - - thread->run(thread->mddev); + if (test_and_clear_bit(THREAD_WAKEUP, &thread->flags)) + thread->run(thread->mddev); } return 0; --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -2396,13 +2396,13 @@ static int run(mddev_t *mddev) return 0; out_free_conf: + md_unregister_thread(mddev->thread); if (conf->r10bio_pool) mempool_destroy(conf->r10bio_pool); safe_put_page(conf->tmppage); kfree(conf->mirrors); kfree(conf); mddev->private = NULL; - md_unregister_thread(mddev->thread); out: return -EIO; }
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