CVE-2025-68756 — block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock

blk_mq_{add,del}_queue_tag_set() functions add and remove queues from tagset, the functions make sure that tagset and queues are marked as shared when two or more queues are attached to the same tagset. Initially a tagset starts as unshared and when the number of added queues reaches two, blk_mq_add_queue_tag_set() marks it as shared along with all the queues attached to it. When the number of attached queues drops to 1 blk_mq_del_queue_tag_set() need to mark both the tagset and the remaining queues as unshared.

Both functions need to freeze current queues in tagset before setting on unsetting BLK_MQ_F_TAG_QUEUE_SHARED flag. While doing so, both functions hold set->tag_list_lock mutex, which makes sense as we do not want queues to be added or deleted in the process. This used to work fine until commit 98d81f0df70c ("nvme: use blk_mq_[un]quiesce_tagset") made the nvme driver quiesce tagset instead of quiscing individual queues. blk_mq_quiesce_tagset() does the job and quiesce the queues in set->tag_list while holding set->tag_list_lock also.

This results in deadlock between two threads with these stacktraces:

__schedule+0x47c/0xbb0 ? timerqueue_add+0x66/0xb0 schedule+0x1c/0xa0 schedule_preempt_disabled+0xa/0x10 __mutex_lock.constprop.0+0x271/0x600 blk_mq_quiesce_tagset+0x25/0xc0 nvme_dev_disable+0x9c/0x250 nvme_ti…

USN-8094-1 — linux, linux-aws, linux-aws-6.17, linux-gcp, linux-hwe-6.17, linux-oracle, linux-oracle-6.17 vulnerabilities

Affected: Ubuntu:24.04:LTS: linux-aws-6.17, Ubuntu:24.04:LTS: linux-hwe-6.17, Ubuntu:24.04:LTS: linux-oracle-6.17, Ubuntu:25.10: linux, Ubuntu:25.10: linux-aws, Ubuntu:25.10: linux-gcp, Ubuntu:25.10: linux-oracle

Qualys discovered that several vulnerabilities existed in the AppArmor Linux kernel Security Module (LSM). An unprivileged local attacker could use these issues to load, replace, and remove arbitrary AppArmor profiles causing denial of service, exposure of sensitive information (kernel memory), local privilege escalation, or possibly escape a container. (LP: #2143853)

It was discovered that some AMD Zen 5 processors supporting RDSEED instruction did not properly handle entropy, potentially resulting in the consumption of insufficiently random values. A local attacker could possibly use this issue to influence the values returned by the RDSEED instruction causing loss of confidentiality and integrity. (CVE-2025-62626)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Cryptographic API; - Compute Acceleration Framework; - ATM drivers; - Network block device driver; - Bluetooth drivers; - Data acquisition framework and drivers; - Hardware crypto device drivers; - Device frequency scaling framework; - Intel Stratix 10 firmware drivers; - GPIO subsystem; - GPU drivers; - Microsoft Hyper-V drivers; - CoreSight HW tracing drivers; - IIO subsystem; - InfiniBand drivers; - Input Device core drivers; - Input Device (Tablet) d…

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CVE-2025-68756 — block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock

USN-8094-1 — linux, linux-aws, linux-aws-6.17, linux-gcp, linux-hwe-6.17, linux-oracle, linux-oracle-6.17 vulnerabilities