CVE-2024-26671 Information

Apr 03, 2024 cve

Description

In the Linux kernel the following vulnerability has been resolved:

blk-mq: fix IO hang from sbitmap wakeup race

In blk_mq_mark_tag_wait() __add_wait_queue() may be re-ordered with the following blk_mq_get_driver_tag() in case of getting driver tag failure.

Then in __sbitmap_queue_wake_up() waitqueue_active() may not observe the added waiter in blk_mq_mark_tag_wait() and wake up nothing meantime blk_mq_mark_tag_wait() can’t get driver tag successfully.

This issue can be reproduced by running the following test in loop and fio hang can be observed in < 30min when running it on my test VM in laptop.

modprobe -r scsi_debug
modprobe scsi_debug delay=0 dev_size_mb=4096 max_queue=1 host_max_queue=1 submit_queues=4
dev=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter/host/target//block/ | head -1 | xargs basename`
fio --filename=/dev/\$dev\ --direct=1 --rw=randrw --bs=4k --iodepth=1 \
   		--runtime=100 --numjobs=40 --time_based --name=test \
    	--ioengine=libaio

Fix the issue by adding one explicit barrier in blk_mq_mark_tag_wait() which is just fine in case of running out of tag.

Reference

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