CVE-2026-23148: nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-14 · updated 2026-10-19
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference There is a race condition in nvmet_bio_done() that can cause a NULL pointer dereference in blk_cgroup_bio_start(): 1. nvmet_bio_done() is called when a bio completes 2. nvmet_req_complete() is called, which invokes req->ops->queue_response(req) 3. The queue_response callback can re-queue and re-submit the same request 4. The re-submission reuses the same inline_bio from nvmet_req 5. Meanwhile, nvmet_req_bio_put() (called after nvmet_req_complete) invokes bio_uninit() for inline_bio, which sets bio->bi_blkg to NULL 6. The re-submitted bio enters submit_bio_noacct_nocheck() 7. blk_cgroup_bio_start() dereferences bio->bi_blkg, causing a crash: BUG: kernel NULL pointer dereference, address: 0000000000000028 #PF: supervisor read access in kernel mode RIP: 0010:blk_cgroup_bio_start+0x10/0xd0 Call Trace: submit_bio_noacct_nocheck+0x44/0x250 nvmet_bdev_execute_rw+0x254/0x370 [nvmet] process_one_work+0x193/0x3c0 worker_thread+0x281/0x3a0 Fix this by reordering nvmet_bio_done() to call nvmet_req_bio_put() BEFORE nvmet_req_complete(). This ensures the bio is cleaned up before the request can be re-submitted, preventing the race condition.

Affected products

Linux kernel: from 6.12.37 before 6.12.69; from 6.15.6 before 6.16; from 6.16.1 before 6.18.9; 6.16, 6.16-rc5, 6.16-rc6, 6.16-rc7, 6.19-rc1, 6.19-rc2 (+5) — fixed in 6.12.69, 6.16, 6.18.9

How to fix

Upgrade to a fixed version: Linux kernel 6.12.69, 6.16, 6.18.9. Check the vendor advisory for mitigations.

References

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