CVE-2026-43466 — net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery

Affected: Linux

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

net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery

In case of a TX error CQE, a recovery flow is triggered, mlx5e_reset_txqsq_cc_pc() resets dma_fifo_cc to 0 but not dma_fifo_pc, desyncing the DMA FIFO producer and consumer.

After recovery, the producer pushes new DMA entries at the old dma_fifo_pc, while the consumer reads from position 0. This causes us to unmap stale DMA addresses from before the recovery.

The DMA FIFO is a purely software construct with no HW counterpart. At the point of reset, all WQEs have been flushed so dma_fifo_cc is already equal to dma_fifo_pc. There is no need to reset either counter, similar to how skb_fifo pc/cc are untouched.

Remove the 'dma_fifo_cc = 0' reset.

This fixes the following WARNING: WARNING: CPU: 0 PID: 0 at drivers/iommu/dma-iommu.c:1240 iommu_dma_unmap_page+0x79/0x90 Modules linked in: mlx5_vdpa vringh vdpa bonding mlx5_ib mlx5_vfio_pci ipip mlx5_fwctl tunnel4 mlx5_core ib_ipoib geneve ip6_gre ip_gre gre nf_tables ip6_tunnel rdma_ucm ib_uverbs ib_umad vfio_pci vfio_pci_core act_mirred act_skbedit act_vlan vhost_net vhost tap ip6table_mangle ip6table_nat ip6table_filter ip6_tables iptable_mangle cls_matchall nfnetlink_cttimeout act_gact cls_flower sch_ingress vhost_iotlb iptable_raw tunnel6 vfio_iommu_type1 vfio openvswitch nsh rpcsec_gss_krb5 auth_rpcgss oid_registry xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink iptable_nat nf_nat x…

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CVE-2026-43466 — net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery