6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Damien Le Moal <dlemoal@xxxxxxxxxx> commit d9ff882b54f99f96787fa3df7cd938966843c418 upstream. When powering on a null_blk device that is not already on, the return value ret that is initialized to be count is reused to check the return value of null_add_dev(), leading to nullb_device_power_store() to return null_add_dev() return value (0 on success) instead of "count". So make sure to set ret to be equal to count when there are no errors. Fixes: a2db328b0839 ("null_blk: fix null-ptr-dereference while configuring 'power' and 'submit_queues'") Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx> Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx> Reviewed-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20240527043445.235267-1-dlemoal@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Xiangyu Chen <xiangyu.chen@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/block/null_blk/main.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/block/null_blk/main.c +++ b/drivers/block/null_blk/main.c @@ -470,6 +470,7 @@ static ssize_t nullb_device_power_store( set_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags); dev->power = newp; + ret = count; } else if (dev->power && !newp) { if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) { dev->power = newp;