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CVE-2021-47399: ixgbe: Fix NULL pointer dereference in ixgbe_xdp_setup

In the Linux kernel, the following vulnerability has been resolved: ixgbe: Fix NULL pointer dereference in ixgbe_xdp_setup The ixgbe driver currently generates a NULL pointer dereference with some machine (online cpus < 63). This is due to the fact that the maximum value of num_xdp_queues is nr_cpu_ids. Code is in "ixgbe_set_rss_queues"". Here's how the problem repeats itself: Some machine (online cpus < 63), And user set num_queues to 63 through ethtool. Code is in the "ixgbe_set_channels", adapter->ring_feature[RING_F_FDIR].limit = count; It becomes 63. When user use xdp, "ixgbe_set_rss_queues" will set queues num. adapter->num_rx_queues = rss_i; adapter->num_tx_queues = rss_i; adapter->num_xdp_queues = ixgbe_xdp_queues(adapter); And rss_i's value is from f = &adapter->ring_feature[RING_F_FDIR]; rss_i = f->indices = f->limit; So "num_rx_queues" > "num_xdp_queues", when run to "ixgbe_xdp_setup", for (i = 0; i < adapter->num_rx_queues; i++) if (adapter->xdp_ring[i]->xsk_umem) It leads to panic. Call trace: [exception RIP: ixgbe_xdp+368] RIP: ffffffffc02a76a0 RSP: ffff9fe16202f8d0 RFLAGS: 00010297 RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 000000000000001c RDI: ffffffffa94ead90 RBP: ffff92f8f24c0c18 R8: 0000000000000000 R9: 0000000000000000 R10: ffff9fe16202f830 R11: 0000000000000000 R12: ffff92f8f24c0000 R13: ffff9fe16202fc01 R14: 000000000000000a R15: ffffffffc02a7530 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 7 [ffff9fe16202f8f0] dev_xdp_install at ffffffffa89fbbcc 8 [ffff9fe16202f920] dev_change_xdp_fd at ffffffffa8a08808 9 [ffff9fe16202f960] do_setlink at ffffffffa8a20235 10 [ffff9fe16202fa88] rtnl_setlink at ffffffffa8a20384 11 [ffff9fe16202fc78] rtnetlink_rcv_msg at ffffffffa8a1a8dd 12 [ffff9fe16202fcf0] netlink_rcv_skb at ffffffffa8a717eb 13 [ffff9fe16202fd40] netlink_unicast at ffffffffa8a70f88 14 [ffff9fe16202fd80] netlink_sendmsg at ffffffffa8a71319 15 [ffff9fe16202fdf0] sock_sendmsg at ffffffffa89df290 16 [ffff9fe16202fe08] __sys_sendto at ffffffffa89e19c8 17 [ffff9fe16202ff30] __x64_sys_sendto at ffffffffa89e1a64 18 [ffff9fe16202ff38] do_syscall_64 at ffffffffa84042b9 19 [ffff9fe16202ff50] entry_SYSCALL_64_after_hwframe at ffffffffa8c0008c So I fix ixgbe_max_channels so that it will not allow a setting of queues to be higher than the num_online_cpus(). And when run to ixgbe_xdp_setup, take the smaller value of num_rx_queues and num_xdp_queues.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-47399 is a Linux kernel bug in the ixgbe network driver. Under specific queue and XDP conditions, the driver can dereference a NULL pointer and panic the kernel. The business impact is primarily availability loss on affected Linux systems using this driver path.

Executive priority

Treat this as a targeted availability issue. Patch exposed ixgbe/XDP systems through normal kernel maintenance, faster for critical network infrastructure. It does not currently justify emergency response based on the provided exploitation evidence.

Technical view

The ixgbe XDP setup path can iterate over RX queues beyond allocated XDP queues after queue counts are set higher than online CPUs. Accessing adapter->xdp_ring[i]->xsk_umem can hit NULL and trigger a kernel panic. The source says fixes bound channel counts and use the smaller RX/XDP queue count.

Likely exposure

Exposure appears limited to Linux systems using the ixgbe driver, relevant kernel versions, and XDP or related queue configuration. The provided data lists Linux as affected and names version markers, but does not provide distribution-specific package status.

Exploitation context

No CISA KEV listing or cited source indicates active exploitation. The described trigger requires changing queue/channel configuration and then using XDP, so the evidence points to a configuration-triggered denial-of-service risk rather than remote code execution.

Researcher notes

The source describes a NULL pointer dereference in ixgbe_xdp_setup caused by num_rx_queues exceeding num_xdp_queues. Fixed commits adjust ixgbe_max_channels and bound iteration by the smaller queue count. Affected-version evidence is sparse and should be mapped through downstream kernel advisories.

Mitigation direction

  • Check vendor or distribution advisories for kernels containing the ixgbe fixes.
  • Prioritize patching Linux systems using ixgbe with XDP or custom queue settings.
  • Avoid unsupported queue counts on ixgbe systems until patched.
  • Do not test panic-triggering conditions on production systems.

Validation and detection

  • Inventory Linux hosts using the ixgbe driver.
  • Identify systems running XDP with ixgbe interfaces.
  • Compare installed kernel packages against vendor fixed versions.
  • Review change history for custom ethtool channel or queue settings.
  • Confirm no production systems rely on vulnerable kernel builds.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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0CVSS vectors
3Timeline events
2ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

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  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4a9b32f30f805ca596d76605903a48eab58e0b88, 4a9b32f30f805ca596d76605903a48eab58e0b88, 4a9b32f30f805ca596d76605903a48eab58e0b88unaffected
LinuxLinux5.0, 0, 5.10.71, 5.14.10, 5.15affected
Weakness

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