CVE-2021-47412block: don't call rq_qos_ops->done_bio if the bio isn't tracked

Official 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/db60edbfff332a6a5477c367af8125f034570989
• https://git.kernel.org/stable/c/004b8f8a691205a93d9e80d98b786b2b97424d6e
• https://git.kernel.org/stable/c/a647a524a46736786c95cdb553a070322ca096e3
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html