3.11.10.3 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Durgin <josh.durgin@xxxxxxxxxxx> commit 9875201e10496612080e7d164acc8f625c18725c upstream. Removing a device deallocates the disk, unschedules the watch, and finally cleans up the rbd_dev structure. rbd_dev_refresh(), called from the watch callback, updates the disk size and rbd_dev structure. With no locking between them, rbd_dev_refresh() may use the device or rbd_dev after they've been freed. To fix this, check whether RBD_DEV_FLAG_REMOVING is set before updating the disk size in rbd_dev_refresh(). In order to prevent a race where rbd_dev_refresh() is already revalidating the disk when rbd_remove() is called, move the call to rbd_bus_del_dev() after the watch is unregistered and all notifies are complete. It's safe to defer deleting this structure because no new requests can be submitted once the RBD_DEV_FLAG_REMOVING is set, since the device cannot be opened. Fixes: http://tracker.ceph.com/issues/5636 Signed-off-by: Josh Durgin <josh.durgin@xxxxxxxxxxx> Reviewed-by: Alex Elder <elder@xxxxxxxxxx> Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx> --- drivers/block/rbd.c | 40 +++++++++++++++++++++++++++++++++------- 1 file changed, 33 insertions(+), 7 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index d88a27d..0f5307f 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -3325,6 +3325,31 @@ static void rbd_exists_validate(struct rbd_device *rbd_dev) clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags); } +static void rbd_dev_update_size(struct rbd_device *rbd_dev) +{ + sector_t size; + bool removing; + + /* + * Don't hold the lock while doing disk operations, + * or lock ordering will conflict with the bdev mutex via: + * rbd_add() -> blkdev_get() -> rbd_open() + */ + spin_lock_irq(&rbd_dev->lock); + removing = test_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags); + spin_unlock_irq(&rbd_dev->lock); + /* + * If the device is being removed, rbd_dev->disk has + * been destroyed, so don't try to update its size + */ + if (!removing) { + size = (sector_t)rbd_dev->mapping.size / SECTOR_SIZE; + dout("setting size to %llu sectors", (unsigned long long)size); + set_capacity(rbd_dev->disk, size); + revalidate_disk(rbd_dev->disk); + } +} + static int rbd_dev_refresh(struct rbd_device *rbd_dev) { u64 mapping_size; @@ -3344,12 +3369,7 @@ static int rbd_dev_refresh(struct rbd_device *rbd_dev) up_write(&rbd_dev->header_rwsem); if (mapping_size != rbd_dev->mapping.size) { - sector_t size; - - size = (sector_t)rbd_dev->mapping.size / SECTOR_SIZE; - dout("setting size to %llu sectors", (unsigned long long)size); - set_capacity(rbd_dev->disk, size); - revalidate_disk(rbd_dev->disk); + rbd_dev_update_size(rbd_dev); } return ret; @@ -5160,7 +5180,6 @@ static ssize_t rbd_remove(struct bus_type *bus, if (ret < 0 || already) return ret; - rbd_bus_del_dev(rbd_dev); ret = rbd_dev_header_watch_sync(rbd_dev, false); if (ret) rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret); @@ -5171,6 +5190,13 @@ static ssize_t rbd_remove(struct bus_type *bus, */ dout("%s: flushing notifies", __func__); ceph_osdc_flush_notifies(&rbd_dev->rbd_client->client->osdc); + /* + * Don't free anything from rbd_dev->disk until after all + * notifies are completely processed. Otherwise + * rbd_bus_del_dev() will race with rbd_watch_cb(), resulting + * in a potential use after free of rbd_dev->disk or rbd_dev. + */ + rbd_bus_del_dev(rbd_dev); rbd_dev_image_release(rbd_dev); module_put(THIS_MODULE); -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html