blk-mq: check kobject state_in_sysfs before deleting in blk_mq_unregister_hctx

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: blk-mq: check kobject state_in_sysfs before deleting in blk_mq_unregister_hctx In __blk_mq_update_nr_hw_queues() the return value of blk_mq_sysfs_register_hctxs() is not checked. If sysfs creation for hctx fails, later changing the number of hw_queues or removing disk will trigger the following warning: kernfs: can not remove 'nr_tags', no directory WARNING: CPU: 2 PID: 637 at fs/kernfs/dir.c:1707 kernfs_remove_by_name_ns+0x13f/0x160 Call Trace: remove_files.isra.1+0x38/0xb0 sysfs_remove_group+0x4d/0x100 sysfs_remove_groups+0x31/0x60 __kobject_del+0x23/0xf0 kobject_del+0x17/0x40 blk_mq_unregister_hctx+0x5d/0x80 blk_mq_sysfs_unregister_hctxs+0x94/0xd0 blk_mq_update_nr_hw_queues+0x124/0x760 nullb_update_nr_hw_queues+0x71/0xf0 [null_blk] nullb_device_submit_queues_store+0x92/0x120 [null_blk] kobjct_del() was called unconditionally even if sysfs creation failed. Fix it by checkig the kobject creation statusbefore deleting it.

References

• https://git.kernel.org/stable/c/a8c53553f1833cc2d14175d2d72cf37193a01898
• https://git.kernel.org/stable/c/cc14ea21c4e658814d737ed4dedde6cd626a15ad
• https://git.kernel.org/stable/c/4b97e99b87a773d52699521d40864f3ec888e9a6
• https://git.kernel.org/stable/c/6e7dadc5763c48eb3b9b91265a21f312599ebb2c
• https://git.kernel.org/stable/c/06c4826b1d900611096e4621e93133db57e13911
• https://git.kernel.org/stable/c/babc634e9fe2803962dba98a07587e835dbc0731
• https://git.kernel.org/stable/c/d5ddd76ee52bdc16e9f8b1e7791291e785dab032
• https://git.kernel.org/stable/c/4c7ef92f6d4d08a27d676e4c348f4e2922cab3ed