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raid5-cache: fix a user-after-free bug 

r5l_compress_stripe_end_list() can free an io_unit. This breaks the
assumption only reclaimer can free io_unit. We can add a reference count
based io_unit free, but since only reclaim can wait io_unit becoming to
STRIPE_END state, we use a simple global wait queue here.

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
This commit is contained in:
Shaohua Li 2015-09-02 13:49:47 -07:00 committed by NeilBrown
parent a8c34f9159
commit 0fd22b45b2
1 changed files with 7 additions and 11 deletions
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18
drivers/md/raid5-cache.c
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@ -79,6 +79,7 @@ struct r5l_log {
* dones't wait for specific io_unit
* switching to IO_UNIT_STRIPE_END
* state) */
wait_queue_head_t iounit_wait;
struct list_head no_space_stripes; /* pending stripes, log has no space */
spinlock_t no_space_stripes_lock;
@ -109,7 +110,6 @@ struct r5l_io_unit {
struct list_head stripe_list; /* stripes added to the io_unit */
int state;
wait_queue_head_t wait_state;
};
/* r5l_io_unit state */
@ -162,7 +162,6 @@ static struct r5l_io_unit *r5l_alloc_io_unit(struct r5l_log *log)
INIT_LIST_HEAD(&io->log_sibling);
INIT_LIST_HEAD(&io->stripe_list);
io->state = IO_UNIT_RUNNING;
init_waitqueue_head(&io->wait_state);
return io;
}
@ -243,8 +242,8 @@ static void __r5l_set_io_unit_state(struct r5l_io_unit *io,
r5l_wake_reclaim(log, 0);
r5l_compress_stripe_end_list(log);
wake_up(&log->iounit_wait);
}
wake_up(&io->wait_state);
}
static void r5l_set_io_unit_state(struct r5l_io_unit *io,
@ -622,10 +621,11 @@ void r5l_flush_stripe_to_raid(struct r5l_log *log)
submit_bio(WRITE_FLUSH, &log->flush_bio);
}
static void r5l_kick_io_unit(struct r5l_log *log, struct r5l_io_unit *io)
static void r5l_kick_io_unit(struct r5l_log *log)
{
md_wakeup_thread(log->rdev->mddev->thread);
wait_event(io->wait_state, io->state >= IO_UNIT_STRIPE_END);
wait_event_lock_irq(log->iounit_wait, !list_empty(&log->stripe_end_ios),
log->io_list_lock);
}
static void r5l_write_super(struct r5l_log *log, sector_t cp);
@ -670,12 +670,7 @@ static void r5l_do_reclaim(struct r5l_log *log)
else if (!list_empty(&log->running_ios))
target_list = &log->running_ios;
io = list_first_entry(target_list,
struct r5l_io_unit, log_sibling);
spin_unlock_irq(&log->io_list_lock);
/* nobody else can delete the io, we are safe */
r5l_kick_io_unit(log, io);
spin_lock_irq(&log->io_list_lock);
r5l_kick_io_unit(log);
}
spin_unlock_irq(&log->io_list_lock);
@ -1079,6 +1074,7 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
log->rdev->mddev, "reclaim");
if (!log->reclaim_thread)
goto reclaim_thread;
init_waitqueue_head(&log->iounit_wait);
INIT_LIST_HEAD(&log->no_space_stripes);
spin_lock_init(&log->no_space_stripes_lock);