CVE-2026-98050: mlxsw: spectrum_ptp: Fix napi_gro_receive() call from GC workqueue context

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

mlxsw: spectrumptp: Fix napigroreceive() call from GC workqueue context

Currently mlxswsp1ptphtgccollect() is run from the PTP garbage-collection workqueue, rather than the NAPI poll context. For any unmatched PTP entries carrying an SKB, it calls mlxswsp1ptpunmatchedfinish() -> mlxswsp1ptppacketfinish(). For ingress packets, this calls mlxswsprxlistenernomarkfunc(). The end of that function is the following:

skb->protocol = ethtypetrans(skb, skb->dev); napigroreceive(mlxswskbcb(skb)->rxmdinfo.napi, skb);

The napi pointer is one that was placed in the SKB control block when the trapped packet was received in the NAPI context. Later, when the GC reaps the unmatched entry (up to MLXSWSP1PTPHTGCTIMEOUT later), the call to napigroreceive() mutates the NAPI instance's GRO list, which is unsafe if the poll is running concurrently on another CPU.

In mlxswsp1ptphtgccollect(), localbhdisable() is called to prevent softirq processing, but this only applies to the local CPU. Additionally, its comment is stale. It states that mlxswsp1ptpunmatchedfinish() invokes netifreceiveskb(). This has not been accurate since the referenced commit; this patch makes that comment accurate again. mlxswpcinapidevsinit() calls netifthreadedenable() on the NAPI RX netdevice without any conditions. The NAPI instance's poll, which may be running concurrent to the GC, is running as an independently-scheduled kthread which may be on a different CPU. The call to localbhdisable() does not guard against this.

If a tx-timestamp timeout produces an unmatched entry (which can be easily reproduced by running ptp4l and waiting for a port to reach the UNCALIBRATED/SLAVE state) while the owning NAPI thread is in the middle of a poll on another CPU, both sides mutate the GRO list concurrently, as shown below:

[39.846] port 1 (swp1): MASTER to UNCALIBRATED on RSSLAVE listadd corruption. next->prev should be prev (ffff8d620faf4138), but was ffff8d624150f700. (next=ffff8d620faf4138). kernel BUG at lib/listdebug.c:29! Oops: invalid opcode: 0000 [#1] SMP PTI CPU: 1 UID: 0 PID: 539 Comm: napi/mlxswrx-0 Not tainted 6.18.48 #1-NixOS PREEMPT(lazy) Hardware name: Mellanox Technologies Ltd. MSN2410/VMOD0001, BIOS 4.6.5 09/13/2018 RIP: 0010:listaddvalidorreport+0x79/0xb0 RSP: 0018:ffffcdf8c0f27c08 EFLAGS: 00010246 RAX: 0000000000000075 RBX: ffff8d624150fd00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8d6315d1e540 RBP: ffff8d620faf4070 R08: 0000000000000000 R09: 00000000ffffdfff R10: ffffffffa5c60fe0 R11: ffffcdf8c0f27ab8 R12: 0000000000000003 R13: 000000000000003d R14: 00000000000001bc R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8d636f63f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000562689a60c24 CR3: 000000015f224004 CR4: 00000000001726f0 Call Trace: <TASK> groreceiveskb+0xee/0x230 mlxswsp1ptpgotpacket+0x61/0x140 [mlxswspectrum] mlxswcoreskbreceive+0xdf/0x1b0 [mlxswcore] mlxswpcinapipollcqrx+0x780/0x9d0 [mlxswpci] napipoll+0x31/0x1e0 napithreadedpollloop+0x16b/0x1c0 napithreadedpoll+0x71/0xa0 kthread+0xfb/0x260 retfromfork+0x22d/0x260 retfromforkasm+0x1a/0x30 </TASK> Kernel panic - not syncing: Fatal exception in interrupt

The machinery that leads to this kernel panic has not been changed between 6.18.48 and mainline.

This patch adds an ingress-delivery helper for the PTP packetfinish() path that calls netifreceiveskb() instead of napigroreceive(). netifreceiveskb(), unlike napigroreceive(), can be called from outside of the NAPI instance's poll context, which can occur at the call site for this path. RX stats accounting and the skb->dev assignment are still preserved; the only change is the delivery call itself.

This removes GR ---truncated---