CVE-2024-26671

Status: AnalyzedMedium (4.7)—

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.

Read full descriptionShow less

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.

Technical details traces, logs and code from the original report

	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

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Base score: 4.7

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.19%
Percentile among all scored CVEs: 7
Score date: 10/8/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (2)

Debian — Debian Linux Linux — Linux Kernel

CWEs

CWE-362

References

Raw JSON (NVD)

Show

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-mq: fix IO hang from sbitmap wakeup race\n\nIn blk_mq_mark_tag_wait(), __add_wait_queue() may be re-ordered\nwith the following blk_mq_get_driver_tag() in case of getting driver\ntag failure.\n\nThen in __sbitmap_queue_wake_up(), waitqueue_active() may not observe\nthe added waiter in blk_mq_mark_tag_wait() and wake up nothing, meantime\nblk_mq_mark_tag_wait() can't get driver tag successfully.\n\nThis issue can be reproduced by running the following test in loop, and\nfio hang can be observed in < 30min when running it on my test VM\nin laptop.\n\n\tmodprobe -r scsi_debug\n\tmodprobe scsi_debug delay=0 dev_size_mb=4096 max_queue=1 host_max_queue=1 submit_queues=4\n\tdev=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/* | head -1 | xargs basename`\n\tfio --filename=/dev/\"$dev\" --direct=1 --rw=randrw --bs=4k --iodepth=1 \\\n       \t\t--runtime=100 --numjobs=40 --time_based --name=test \\\n        \t--ioengine=libaio\n\nFix the issue by adding one explicit barrier in blk_mq_mark_tag_wait(), which\nis just fine in case of running out of tag."
    },
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      "value": "En el kernel de Linux, se resolvió la siguiente vulnerabilidad: blk-mq: corrige el bloqueo de IO de la carrera de activación del mapa de bits En blk_mq_mark_tag_wait(), __add_wait_queue() se puede reordenar con el siguiente blk_mq_get_driver_tag() en caso de que se produzca un error en la etiqueta del controlador. Luego, en __sbitmap_queue_wake_up(), waitqueue_active() puede no observar al camarero agregado en blk_mq_mark_tag_wait() y no despertar nada, mientras tanto, blk_mq_mark_tag_wait() no puede obtener la etiqueta del controlador correctamente. Este problema se puede reproducir ejecutando la siguiente prueba en bucle, y se puede observar un bloqueo de fio en &lt; 30 minutos cuando lo ejecuto en mi máquina virtual de prueba en una computadora portátil. modprobe -r scsi_debug modprobe scsi_debug delay=0 dev_size_mb=4096 max_queue=1 host_max_queue=1 submit_queues=4 dev=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block /* | cabeza -1 | xargs basename` fio --filename=/dev/\"$dev\" --direct=1 --rw=randrw --bs=4k --io Depth=1 \\ --runtime=100 --numjobs=40 --time_based - -name=test \\ --ioengine=libaio Solucione el problema agregando una barrera explícita en blk_mq_mark_tag_wait(), lo cual está bien en caso de quedarse sin etiqueta."
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  "lastModified": "2026-06-17T07:18:03.443",
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