Bug 2468160 (CVE-2026-43466)
| Summary: | CVE-2026-43466 kernel: net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery | ||
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| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | unspecified | CC: | rhel-process-autobot, watson-tool-maintainers |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in the Linux kernel's mlx5e network driver. During a transmit (TX) error recovery process, a desynchronization occurs in the Direct Memory Access (DMA) First-In, First-Out (FIFO) buffer. This desynchronization causes the system to incorrectly unmap memory addresses, which can lead to memory corruption. This issue could result in a system crash, causing a denial of service.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
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 xt_addrtype br_netfilter overlay zram zsmalloc rpcrdma ib_iser libiscsi scsi_transport_iscsi rdma_cm iw_cm ib_cm ib_core fuse [last unloaded: nf_tables] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.13.0-rc5_for_upstream_min_debug_2024_12_30_21_33 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:iommu_dma_unmap_page+0x79/0x90 Code: 2b 4d 3b 21 72 26 4d 3b 61 08 73 20 49 89 d8 44 89 f9 5b 4c 89 f2 4c 89 e6 48 89 ef 5d 41 5c 41 5d 41 5e 41 5f e9 c7 ae 9e ff <0f> 0b 5b 5d 41 5c 41 5d 41 5e 41 5f c3 66 2e 0f 1f 84 00 00 00 00 Call Trace: <IRQ> ? __warn+0x7d/0x110 ? iommu_dma_unmap_page+0x79/0x90 ? report_bug+0x16d/0x180 ? handle_bug+0x4f/0x90 ? exc_invalid_op+0x14/0x70 ? asm_exc_invalid_op+0x16/0x20 ? iommu_dma_unmap_page+0x79/0x90 ? iommu_dma_unmap_page+0x2e/0x90 dma_unmap_page_attrs+0x10d/0x1b0 mlx5e_tx_wi_dma_unmap+0xbe/0x120 [mlx5_core] mlx5e_poll_tx_cq+0x16d/0x690 [mlx5_core] mlx5e_napi_poll+0x8b/0xac0 [mlx5_core] __napi_poll+0x24/0x190 net_rx_action+0x32a/0x3b0 ? mlx5_eq_comp_int+0x7e/0x270 [mlx5_core] ? notifier_call_chain+0x35/0xa0 handle_softirqs+0xc9/0x270 irq_exit_rcu+0x71/0xd0 common_interrupt+0x7f/0xa0 </IRQ> <TASK> asm_common_interrupt+0x22/0x40