CVE-2023-53463 ibmvnic: Do not reset dql stats on NON_FATAL err

What is CVE-2023-53463?

CVE-2023-53463 is a high-severity denial of service vulnerability in Linux kernel, published on 1 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

ibmvnic: Do not reset dql stats on NON_FATAL err

All ibmvnic resets, make a call to netdev_tx_reset_queue() when re-opening the device. netdev_tx_reset_queue() resets the num_queued and num_completed byte counters. These stats are used in Byte Queue Limit (BQL) algorithms. The difference between these two stats tracks the number of bytes currently sitting on the physical NIC. ibmvnic increases the number of queued bytes though calls to netdev_tx_sent_queue() in the drivers xmit function. When, VIOS reports that it is done transmitting bytes, the ibmvnic device increases the number of completed bytes through calls to netdev_tx_completed_queue(). It is important to note that the driver batches its transmit calls and num_queued is increased every time that an skb is added to the next batch, not necessarily when the batch is sent to VIOS for transmission.

Unlike other reset types, a NON FATAL reset will not flush the sub crq tx buffers. Therefore, it is possible for the batched skb array to be partially full. So if there is call to netdev_tx_reset_queue() when re-opening the device, the value of num_queued (0) would not account for the skb's that are currently batched. Eventually, when the batch is sent to VIOS, the call to netdev_tx_completed_queue() would increase num_completed to a value greater than the num_queued. This causes a BUG_ON crash:

ibmvnic 30000002: Firmware reports error, cause: adapter problem. Starting recovery... ibmvnic 30000002: tx error 600 ibmvnic 30000002: tx error 600 ibmvnic 30000002: tx error 600 ibmvnic 30000002: tx error 600 ------------[ cut here ]------------ kernel BUG at lib/dynamic_queue_limits.c:27! Oops: Exception in kernel mode, sig: 5 [....] NIP dql_completed+0x28/0x1c0 LR ibmvnic_complete_tx.isra.0+0x23c/0x420 [ibmvnic] Call Trace: ibmvnic_complete_tx.isra.0+0x3f8/0x420 [ibmvnic] (unreliable) ibmvnic_interrupt_tx+0x40/0x70 [ibmvnic] __handle_irq_event_percpu+0x98/0x270 ---[ end trace ]---

Therefore, do not reset the dql stats when performing a NON_FATAL reset.

Which versions are affected by CVE-2023-53463?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2023-53463?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-53463 being exploited?

There is no known exploitation of CVE-2023-53463 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2023-53463, DEBIAN-CVE-2023-53463, GHSA-m8cg-86wh-jh9h, UBUNTU-CVE-2023-53463.