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/"$dev" --direct=1 --rw=randrw --bs=4k --iodepth=1 \ --runtime=100 --numjobs=40 --time_based --name=test \ --ioengine=libaio Fix the issue by adding one explicit barrier in blk_mq_mark_tag_wait(), which is just fine in case of running out of tag.
En el kernel de Linux, se resolvió la siguiente vulnerabilidad: blk-mq: corrige el bloqueo de IO de la carrera de activación del mapa de bits En blk_mq_mark_tag_wait(), __add_wait_queue() se puede reordenar con el siguiente blk_mq_get_driver_tag() en caso de que se produzca un error en la etiqueta del controlador. Luego, en __sbitmap_queue_wake_up(), waitqueue_active() puede no observar al camarero agregado en blk_mq_mark_tag_wait() y no despertar nada, mientras tanto, blk_mq_mark_tag_wait() no puede obtener la etiqueta del controlador correctamente. Este problema se puede reproducir ejecutando la siguiente prueba en bucle, y se puede observar un bloqueo de fio en < 30 minutos cuando lo ejecuto en mi máquina virtual de prueba en una computadora portátil. modprobe -r scsi_debug modprobe scsi_debug delay=0 dev_size_mb=4096 max_queue=1 host_max_queue=1 submit_queues=4 dev=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block /* | cabeza -1 | xargs basename` fio --filename=/dev/"$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.
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | HIGH |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | NONE |
| Integrity Impact | NONE |
| Availability Impact | HIGH |
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-362
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd319dd6100> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd36865ca80> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd369e23a80> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd319dd6400> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd319dd4a00> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd319dd6040> | Operating System |
| debian | debian_linux | 10.0 | <built-in method update of dict object at 0x7fd369407e40> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* |