eth: bnxt: do not update checksum in bnxt_xdp_build_skb()
CVE: CVE-2025-21960
Component: kernel
CWE: CWE-675
Severity: Moderate
CVSS v3: 5.9/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Release date: 2025-04-01T00:00:00+00:00

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

eth: bnxt: do not update checksum in bnxt_xdp_build_skb()

The bnxt_rx_pkt() updates ip_summed value at the end if checksum offload
is enabled.
When the XDP-MB program is attached and it returns XDP_PASS, the
bnxt_xdp_build_skb() is called to update skb_shared_info.
The main purpose of bnxt_xdp_build_skb() is to update skb_shared_info,
but it updates ip_summed value too if checksum offload is enabled.
This is actually duplicate work.

When the bnxt_rx_pkt() updates ip_summed value, it checks if ip_summed
is CHECKSUM_NONE or not.
It means that ip_summed should be CHECKSUM_NONE at this moment.
But ip_summed may already be updated to CHECKSUM_UNNECESSARY in the
XDP-MB-PASS path.
So the by skb_checksum_none_assert() WARNS about it.

This is duplicate work and updating ip_summed in the
bnxt_xdp_build_skb() is not needed.

Splat looks like:
WARNING: CPU: 3 PID: 5782 at ./include/linux/skbuff.h:5155 bnxt_rx_pkt+0x479b/0x7610 [bnxt_en]
Modules linked in: bnxt_re bnxt_en rdma_ucm rdma_cm iw_cm ib_cm ib_uverbs veth xt_nat xt_tcpudp xt_conntrack nft_chain_nat xt_MASQUERADE nf_]
CPU: 3 UID: 0 PID: 5782 Comm: socat Tainted: G        W          6.14.0-rc4+ #27
Tainted: [W]=WARN
Hardware name: ASUS System Product Name/PRIME Z690-P D4, BIOS 0603 11/01/2021
RIP: 0010:bnxt_rx_pkt+0x479b/0x7610 [bnxt_en]
Code: 54 24 0c 4c 89 f1 4c 89 ff c1 ea 1f ff d3 0f 1f 00 49 89 c6 48 85 c0 0f 84 4c e5 ff ff 48 89 c7 e8 ca 3d a0 c8 e9 8f f4 ff ff <0f> 0b f
RSP: 0018:ffff88881ba09928 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 00000000c7590303 RCX: 0000000000000000
RDX: 1ffff1104e7d1610 RSI: 0000000000000001 RDI: ffff8881c91300b8
RBP: ffff88881ba09b28 R08: ffff888273e8b0d0 R09: ffff888273e8b070
R10: ffff888273e8b010 R11: ffff888278b0f000 R12: ffff888273e8b080
R13: ffff8881c9130e00 R14: ffff8881505d3800 R15: ffff888273e8b000
FS:  00007f5a2e7be080(0000) GS:ffff88881ba00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff2e708ff8 CR3: 000000013e3b0000 CR4: 00000000007506f0
PKRU: 55555554
Call Trace:
 <IRQ>
 ? __warn+0xcd/0x2f0
 ? bnxt_rx_pkt+0x479b/0x7610
 ? report_bug+0x326/0x3c0
 ? handle_bug+0x53/0xa0
 ? exc_invalid_op+0x14/0x50
 ? asm_exc_invalid_op+0x16/0x20
 ? bnxt_rx_pkt+0x479b/0x7610
 ? bnxt_rx_pkt+0x3e41/0x7610
 ? __pfx_bnxt_rx_pkt+0x10/0x10
 ? napi_complete_done+0x2cf/0x7d0
 __bnxt_poll_work+0x4e8/0x1220
 ? __pfx___bnxt_poll_work+0x10/0x10
 ? __pfx_mark_lock.part.0+0x10/0x10
 bnxt_poll_p5+0x36a/0xfa0
 ? __pfx_bnxt_poll_p5+0x10/0x10
 __napi_poll.constprop.0+0xa0/0x440
 net_rx_action+0x899/0xd00
...

Following ping.py patch adds xdp-mb-pass case. so ping.py is going
to be able to reproduce this issue.

Statement: The bug is actual only if XDP (eXpress Data Path) that is an eBPF-based high-performance network data path being used. The bug doesn't lead to kernel crash, so only about annoying warning message.

Remediation:
To mitigate this issue, prevent module bnxt_en from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.