ibmvnic: Do not reset dql stats on NON_FATAL err
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 5.15.121, 6.1.39, 6.4.4
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
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.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- Linux Linux
From 0d973388185d49add56b81ca82fa5e4348019df8 · fixed in b8aedf29db1280c83191fc9579ae605791faf97f; From 0d973388185d49add56b81ca82fa5e4348019df8 · fixed in f67ef8f9f6776e2b2073cad7c5cf29de850f83d7; From 0d973388185d49add56b81ca82fa5e4348019df8 · fixed in 91a0632e73070928aafeb36b3cc676843c716931; From 0d973388185d49add56b81ca82fa5e4348019df8 · fixed in 48538ccb825b05544ec308a509e2cc9c013402db
- Linux Linux
5.11
- KernelLinux
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