block: Fix possible memory leak for rq_wb on add_disk failure

Summary

In the Linux kernel, the following vulnerability has been resolved: block: Fix possible memory leak for rq_wb on add_disk failure kmemleak reported memory leaks in device_add_disk(): kmemleak: 3 new suspected memory leaks unreferenced object 0xffff88800f420800 (size 512): comm "modprobe", pid 4275, jiffies 4295639067 (age 223.512s) hex dump (first 32 bytes): 04 00 00 00 08 00 00 00 01 00 00 00 00 00 00 00 ................ 00 e1 f5 05 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000d3662699>] kmalloc_trace+0x26/0x60 [<00000000edc7aadc>] wbt_init+0x50/0x6f0 [<0000000069601d16>] wbt_enable_default+0x157/0x1c0 [<0000000028fc393f>] blk_register_queue+0x2a4/0x420 [<000000007345a042>] device_add_disk+0x6fd/0xe40 [<0000000060e6aab0>] nbd_dev_add+0x828/0xbf0 [nbd] ... It is because the memory allocated in wbt_enable_default() is not released in device_add_disk() error path. Normally, these memory are freed in: del_gendisk() rq_qos_exit() rqos->ops->exit(rqos); wbt_exit() So rq_qos_exit() is called to free the rq_wb memory for wbt_init(). However in the error path of device_add_disk(), only blk_unregister_queue() is called and make rq_wb memory leaked. Add rq_qos_exit() to the error path to fix it.

Timeline

1. May 1, 2025, 2:10 PM UTCCVE published
2. Oct 1, 2025, 2:59 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. May 11, 2026, 7:08 PM UTCRecord last updated

Affected versions

• Linux Linux

  Version range not reported

• Linux Linux

  5.15

References 3