CVE-2021-47412 Information

May 23, 2024 cve

Description

In the Linux kernel the following vulnerability has been resolved:

block: don’t call rq_qos_ops->done_bio if the bio isn’t tracked

rq_qos framework is only applied on request based driver so:

  1. rq_qos_done_bio() needn’t to be called for bio based driver

  2. rq_qos_done_bio() needn’t to be called for bio which isn’t tracked such as bios ended from error handling code.

Especially in bio_endio():

  1. request queue is referred via bio->bi_bdev->bd_disk->queue which may be gone since request queue refcount may not be held in above two cases

  2. q->rq_qos may be freed in blk_cleanup_queue() when calling into __rq_qos_done_bio()

Fix the potential kernel panic by not calling rq_qos_ops->done_bio if the bio isn’t tracked. This way is safe because both ioc_rqos_done_bio() and blkcg_iolatency_done_bio() are nop if the bio isn’t tracked.

Reference

https://git.kernel.org/stable/c/004b8f8a691205a93d9e80d98b786b2b97424d6e https://git.kernel.org/stable/c/a647a524a46736786c95cdb553a070322ca096e3

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