CVE-2022-49902

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.

Affected Software

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://git.kernel.org/stable/c/4e68c5da60cd79950bd56287ae80b39d6261f995
• https://git.kernel.org/stable/c/528677d3b4af985445bd4ac667485ded1ed11220
• https://git.kernel.org/stable/c/fa81cbafbf5764ad5053512152345fab37a1fe18

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