6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zizhi Wo [ Upstream commit 2a6357a9b935a34f5508618fee8a7fffbf7722a8 ] null_init_zoned_dev() allocates dev->zones when a zoned device is powered on, but null_del_dev() never frees it on power-off; dev->zones is only freed later in null_free_dev(), when the configfs directory is removed. If the device is powered off and then on again, null_init_zoned_dev() allocates a new array and overwrites the dev->zones pointer, leaking the previous allocation each power cycle. Free dev->zones in null_del_dev() via null_free_zoned_dev() to solve it. And calling null_free_zoned_dev() in null_free_dev() is no longer necessary because every caller already invokes null_del_dev() first: via nullb_group_drop_item() before nullb_device_release(), in the null_add_dev() error path of null_create_dev(), and in null_destroy_dev(). Remove the redundant call. And take &lock around zone_cond_store() in the two store wrappers to serialize dev->zones check-and-deref against its alloc/free, which already run under &lock. The reason there was no problem before is that only nullb_device_release() or null_exit() frees the dev->zones, which guarantees that subsequent users won't access the configfs interface. Fixes: ca4b2a011948 ("null_blk: add zone support") Assisted-by: Claude-Code:GLM-5.2 Signed-off-by: Zizhi Wo Reviewed-by: Nilay Shroff Reviewed-by: Bart Van Assche Link: https://patch.msgid.link/20260725022509.714271-6-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/null_blk/main.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c index a011ae2055d0c..243565d47eb59 100644 --- a/drivers/block/null_blk/main.c +++ b/drivers/block/null_blk/main.c @@ -552,8 +552,13 @@ static ssize_t nullb_device_zone_readonly_store(struct config_item *item, const char *page, size_t count) { struct nullb_device *dev = to_nullb_device(item); + ssize_t ret; + + mutex_lock(&lock); + ret = zone_cond_store(dev, page, count, BLK_ZONE_COND_READONLY); + mutex_unlock(&lock); - return zone_cond_store(dev, page, count, BLK_ZONE_COND_READONLY); + return ret; } CONFIGFS_ATTR_WO(nullb_device_, zone_readonly); @@ -561,8 +566,13 @@ static ssize_t nullb_device_zone_offline_store(struct config_item *item, const char *page, size_t count) { struct nullb_device *dev = to_nullb_device(item); + ssize_t ret; - return zone_cond_store(dev, page, count, BLK_ZONE_COND_OFFLINE); + mutex_lock(&lock); + ret = zone_cond_store(dev, page, count, BLK_ZONE_COND_OFFLINE); + mutex_unlock(&lock); + + return ret; } CONFIGFS_ATTR_WO(nullb_device_, zone_offline); @@ -785,7 +795,6 @@ static void null_free_dev(struct nullb_device *dev) if (!dev) return; - null_free_zoned_dev(dev); badblocks_exit(&dev->badblocks); kfree(dev); } @@ -1870,6 +1879,7 @@ static void null_del_dev(struct nullb *nullb) } put_disk(nullb->disk); + null_free_zoned_dev(dev); if (dev->queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set) blk_mq_free_tag_set(nullb->tag_set); -- 2.53.0