ghsa-862x-fxfw-xgq9
Vulnerability from github
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.
{
"affected": [],
"aliases": [
"CVE-2025-21682"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-31T12:15:29Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\neth: bnxt: always recalculate features after XDP clearing, fix null-deref\n\nRecalculate features when XDP is detached.\n\nBefore:\n # ip li set dev eth0 xdp obj xdp_dummy.bpf.o sec xdp\n # ip li set dev eth0 xdp off\n # ethtool -k eth0 | grep gro\n rx-gro-hw: off [requested on]\n\nAfter:\n # ip li set dev eth0 xdp obj xdp_dummy.bpf.o sec xdp\n # ip li set dev eth0 xdp off\n # ethtool -k eth0 | grep gro\n rx-gro-hw: on\n\nThe fact that HW-GRO doesn\u0027t get re-enabled automatically is just\na minor annoyance. The real issue is that the features will randomly\ncome back during another reconfiguration which just happens to invoke\nnetdev_update_features(). The driver doesn\u0027t handle reconfiguring\ntwo things at a time very robustly.\n\nStarting with commit 98ba1d931f61 (\"bnxt_en: Fix RSS logic in\n__bnxt_reserve_rings()\") we only reconfigure the RSS hash table\nif the \"effective\" number of Rx rings has changed. If HW-GRO is\nenabled \"effective\" number of rings is 2x what user sees.\nSo if we are in the bad state, with HW-GRO re-enablement \"pending\"\nafter XDP off, and we lower the rings by / 2 - the HW-GRO rings\ndoing 2x and the ethtool -L doing / 2 may cancel each other out,\nand the:\n\n if (old_rx_rings != bp-\u003ehw_resc.resv_rx_rings \u0026\u0026\n\ncondition in __bnxt_reserve_rings() will be false.\nThe RSS map won\u0027t get updated, and we\u0027ll crash with:\n\n BUG: kernel NULL pointer dereference, address: 0000000000000168\n RIP: 0010:__bnxt_hwrm_vnic_set_rss+0x13a/0x1a0\n bnxt_hwrm_vnic_rss_cfg_p5+0x47/0x180\n __bnxt_setup_vnic_p5+0x58/0x110\n bnxt_init_nic+0xb72/0xf50\n __bnxt_open_nic+0x40d/0xab0\n bnxt_open_nic+0x2b/0x60\n ethtool_set_channels+0x18c/0x1d0\n\nAs we try to access a freed ring.\n\nThe issue is present since XDP support was added, really, but\nprior to commit 98ba1d931f61 (\"bnxt_en: Fix RSS logic in\n__bnxt_reserve_rings()\") it wasn\u0027t causing major issues.",
"id": "GHSA-862x-fxfw-xgq9",
"modified": "2025-02-04T15:31:35Z",
"published": "2025-01-31T12:33:03Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21682"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/08831a894d18abfaabb5bbde7c2069a7fb41dd93"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f0aa6a37a3dbb40b272df5fc6db93c114688adcd"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
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