CVE-2026-43314

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

dm: remove fake timeout to avoid leak request

Since commit 15f73f5b3e59 (blk-mq: move failure injection out of blk_mq_complete_request), drivers are responsible for calling blk_should_fake_timeout() at appropriate code paths and opportunities.

However, the dm driver does not implement its own timeout handler and relies on the timeout handling of its slave devices.

If an io-timeout-fail error is injected to a dm device, the request will be leaked and never completed, causing tasks to hang indefinitely.

Reproduce:

1. prepare dm which has iscsi slave device
2. inject io-timeout-fail to dm echo 1 >/sys/class/block/dm-0/io-timeout-fail echo 100 >/sys/kernel/debug/fail_io_timeout/probability echo 10 >/sys/kernel/debug/fail_io_timeout/times
3. read/write dm
4. iscsiadm -m node -u

Result: hang task like below [ 862.243768] INFO: task kworker/u514:2:151 blocked for more than 122 seconds. [ 862.244133] Tainted: G E 6.19.0-rc1+ #51 [ 862.244337] echo 0 > /proc/sys/kernel/hung_task_timeout_secs disables this message. [ 862.244718] task:kworker/u514:2 state:D stack:0 pid:151 tgid:151 ppid:2 task_flags:0x4288060 flags:0x00080000 [ 862.245024] Workqueue: iscsi_ctrl_3:1 __iscsi_unbind_session [scsi_transport_iscsi] [ 862.245264] Call Trace: [ 862.245587] [ 862.245814] __schedule+0x810/0x15c0 [ 862.246557] schedule+0x69/0x180 [ 862.246760] blk_mq_freeze_queue_wait+0xde/0x120 [ 862.247688] elevator_change+0x16d/0x460 [ 862.247893] elevator_set_none+0x87/0xf0 [ 862.248798] blk_unregister_queue+0x12e/0x2a0 [ 862.248995] __del_gendisk+0x231/0x7e0 [ 862.250143] del_gendisk+0x12f/0x1d0 [ 862.250339] sd_remove+0x85/0x130 [sd_mod] [ 862.250650] device_release_driver_internal+0x36d/0x530 [ 862.250849] bus_remove_device+0x1dd/0x3f0 [ 862.251042] device_del+0x38a/0x930 [ 862.252095] __scsi_remove_device+0x293/0x360 [ 862.252291] scsi_remove_target+0x486/0x760 [ 862.252654] __iscsi_unbind_session+0x18a/0x3e0 [scsi_transport_iscsi] [ 862.252886] process_one_work+0x633/0xe50 [ 862.253101] worker_thread+0x6df/0xf10 [ 862.253647] kthread+0x36d/0x720 [ 862.254533] ret_from_fork+0x2a6/0x470 [ 862.255852] ret_from_fork_asm+0x1a/0x30 [ 862.256037]

Remove the blk_should_fake_timeout() check from dm, as dm has no native timeout handling and should not attempt to fake timeouts.

Weakness

The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• For example, languages such as Java, Ruby, and Lisp perform automatic garbage collection that releases memory for objects that have been deallocated.
• Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.
• When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.
• Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/469.html

References

• https://git.kernel.org/stable/c/4f9e7ca933a9fbf9912a384b061a00c77332cbf0
• https://git.kernel.org/stable/c/6cdb21e0c9fdee484feba14fc9e72e9d07daf9f3
• https://git.kernel.org/stable/c/8200fca818c1e2f65bc6cb16d934ff6049302197
• https://git.kernel.org/stable/c/b307b6307f6459841312432bd4bc9519cbac97f5
• https://git.kernel.org/stable/c/c8a23d4c995ef4227bd4de64cd3910637ee6162e
• https://git.kernel.org/stable/c/cf2d06c9fd4b6521ea5b7f73c99c64c2c6f5e224
• https://git.kernel.org/stable/c/ece6720de9403260088209b0b92d45e0b49ff856
• https://git.kernel.org/stable/c/f3a9c95a15d2f4466acad5c68faeff79ca5e9f47