Re: [PATCH v4 4/4] scsi: core: Call blk_mq_free_tag_set() earlier

[Ming Lei <ming.lei@redhat.com>]

On Tue, Jul 12, 2022 at 03:19:36PM -0700, Bart Van Assche wrote:
> There are two .exit_cmd_priv implementations. Both implementations use
> resources associated with the SCSI host. Make sure that these resources are
> still available when .exit_cmd_priv is called by moving the .exit_cmd_priv
> calls from scsi_host_dev_release() to scsi_forget_host(). Moving
> blk_mq_free_tag_set() from scsi_host_dev_release() to scsi_forget_host() is
> safe because scsi_forget_host() waits until all SCSI devices associated
> with the host have been removed.
> 
> This patch fixes the following use-after-free:
> 
> ==================================================================
> BUG: KASAN: use-after-free in srp_exit_cmd_priv+0x27/0xd0 [ib_srp]
> Read of size 8 at addr ffff888100337000 by task multipathd/16727
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x34/0x44
>  print_report.cold+0x5e/0x5db
>  kasan_report+0xab/0x120
>  srp_exit_cmd_priv+0x27/0xd0 [ib_srp]
>  scsi_mq_exit_request+0x4d/0x70
>  blk_mq_free_rqs+0x143/0x410
>  __blk_mq_free_map_and_rqs+0x6e/0x100
>  blk_mq_free_tag_set+0x2b/0x160
>  scsi_host_dev_release+0xf3/0x1a0
>  device_release+0x54/0xe0
>  kobject_put+0xa5/0x120
>  device_release+0x54/0xe0
>  kobject_put+0xa5/0x120
>  scsi_device_dev_release_usercontext+0x4c1/0x4e0
>  execute_in_process_context+0x23/0x90
>  device_release+0x54/0xe0
>  kobject_put+0xa5/0x120
>  scsi_disk_release+0x3f/0x50
>  device_release+0x54/0xe0
>  kobject_put+0xa5/0x120
>  disk_release+0x17f/0x1b0
>  device_release+0x54/0xe0
>  kobject_put+0xa5/0x120
>  dm_put_table_device+0xa3/0x160 [dm_mod]
>  dm_put_device+0xd0/0x140 [dm_mod]
>  free_priority_group+0xd8/0x110 [dm_multipath]
>  free_multipath+0x94/0xe0 [dm_multipath]
>  dm_table_destroy+0xa2/0x1e0 [dm_mod]
>  __dm_destroy+0x196/0x350 [dm_mod]
>  dev_remove+0x10c/0x160 [dm_mod]
>  ctl_ioctl+0x2c2/0x590 [dm_mod]
>  dm_ctl_ioctl+0x5/0x10 [dm_mod]
>  __x64_sys_ioctl+0xb4/0xf0
>  dm_ctl_ioctl+0x5/0x10 [dm_mod]
>  __x64_sys_ioctl+0xb4/0xf0
>  do_syscall_64+0x3b/0x90
>  entry_SYSCALL_64_after_hwframe+0x46/0xb0
> 
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: Mike Christie <michael.christie@oracle.com>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: John Garry <john.garry@huawei.com>
> Cc: Li Zhijian <lizhijian@fujitsu.com>
> Reported-by: Li Zhijian <lizhijian@fujitsu.com>
> Tested-by: Li Zhijian <lizhijian@fujitsu.com>
> Fixes: 65ca846a5314 ("scsi: core: Introduce {init,exit}_cmd_priv()")
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming