NULL Pointer Dereference Affecting kernel-coco_debug package, versions <6.4.0-15061.15.coco15sp6.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.02% (4th percentile)

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  • Snyk IDSNYK-SLES156-KERNELCOCODEBUG-8732061
  • published18 Feb 2025
  • disclosed17 Feb 2025

Introduced: 17 Feb 2025

CVE-2025-21682  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade SLES:15.6 kernel-coco_debug to version 6.4.0-15061.15.coco15sp6.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-coco_debug package and not the kernel-coco_debug package as distributed by SLES. See How to fix? for SLES:15.6 relevant fixed versions and status.

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

eth: bnxt: always recalculate features after XDP clearing, fix null-deref

Recalculate features when XDP is detached.

Before:

ip li set dev eth0 xdp obj xdp_dummy.bpf.o sec xdp

ip li set dev eth0 xdp off

ethtool -k eth0 | grep gro

rx-gro-hw: off [requested on]

After:

ip li set dev eth0 xdp obj xdp_dummy.bpf.o sec xdp

ip li set dev eth0 xdp off

ethtool -k eth0 | grep gro

rx-gro-hw: on

The fact that HW-GRO doesn't get re-enabled automatically is just a minor annoyance. The real issue is that the features will randomly come back during another reconfiguration which just happens to invoke netdev_update_features(). The driver doesn't handle reconfiguring two things at a time very robustly.

Starting with commit 98ba1d931f61 ("bnxt_en: Fix RSS logic in __bnxt_reserve_rings()") we only reconfigure the RSS hash table if the "effective" number of Rx rings has changed. If HW-GRO is enabled "effective" number of rings is 2x what user sees. So if we are in the bad state, with HW-GRO re-enablement "pending" after XDP off, and we lower the rings by / 2 - the HW-GRO rings doing 2x and the ethtool -L doing / 2 may cancel each other out, and the:

if (old_rx_rings != bp->hw_resc.resv_rx_rings &&

condition in __bnxt_reserve_rings() will be false. The RSS map won't get updated, and we'll crash with:

BUG: kernel NULL pointer dereference, address: 0000000000000168 RIP: 0010:__bnxt_hwrm_vnic_set_rss+0x13a/0x1a0 bnxt_hwrm_vnic_rss_cfg_p5+0x47/0x180 __bnxt_setup_vnic_p5+0x58/0x110 bnxt_init_nic+0xb72/0xf50 __bnxt_open_nic+0x40d/0xab0 bnxt_open_nic+0x2b/0x60 ethtool_set_channels+0x18c/0x1d0

As we try to access a freed ring.

The issue is present since XDP support was added, really, but prior to commit 98ba1d931f61 ("bnxt_en: Fix RSS logic in __bnxt_reserve_rings()") it wasn't causing major issues.

CVSS Base Scores

version 3.1