{"id":"CVE-2026-98796","title":"net: ethernet: mtk_eth_soc: allocate dummy netdev sooner","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ethernet: mtk_eth_soc: allocate dummy netdev sooner\n\nThe RX rings and the shared NAPI are carried by an internal \"dummy\" netdev\n(eth->dummy_dev). mtk_probe() creat…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 656e705243fd0c2864b89634ea16ed444ef64dc6 < 42001839e425b2564b7297be579073a13a8fddf6","Linux >= 656e705243fd0c2864b89634ea16ed444ef64dc6 < 82be3d08de9e14d5aed72377f051adb4f09fd540","Linux >= 656e705243fd0c2864b89634ea16ed444ef64dc6 < 17eafd74de5a31e30361420a2e3ebf64186b77e5","Linux >= 656e705243fd0c2864b89634ea16ed444ef64dc6 < 6f0c2c4f5e7143eba75153ecc8af3a03f7b6a98b","Linux 4.6"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:48:40.684Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98796","references":[{"url":"https://git.kernel.org/stable/c/42001839e425b2564b7297be579073a13a8fddf6"},{"url":"https://git.kernel.org/stable/c/82be3d08de9e14d5aed72377f051adb4f09fd540"},{"url":"https://git.kernel.org/stable/c/17eafd74de5a31e30361420a2e3ebf64186b77e5"},{"url":"https://git.kernel.org/stable/c/6f0c2c4f5e7143eba75153ecc8af3a03f7b6a98b"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T16:47:32.484Z","slug":"CVE-2026-98796","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: ethernet: mtk_eth_soc: allocate dummy netdev sooner\n\nThe RX rings and the shared NAPI are carried by an internal \"dummy\" netdev\n(eth->dummy_dev). mtk_probe() creates that dummy device, and adds the\nshared tx/rx NAPI to it, only after the MAC netdevs have been registered.\nThat order has been there since the MT7623 support was added and leaves a\nwindow in which the netdevs are visible to the network core before the\nshared NAPI and the dummy device exist.\n\nIf anything brings the first netdev up during that window (e.g. netifd\nopening the WAN link the instant the interface is registered), the\nfirst-open path runs without them. On NETSYS v2 and later SoCs\nmtk_rx_alloc() -> __xdp_rxq_info_reg() then dereferences eth->dummy_dev ==\nNULL:\n\n  WARNING: CPU: ... Missing net_device from driver\n\nin net/core/xdp.c and mtk_open() fails with -ENODEV. On NETSYS v1 SoCs\n(MT7621/MT7622/MT7623/MT7629) there is no page pool, so the same open\ninstead calls napi_enable() on a napi_struct that netif_napi_add() has not\ninitialised yet and dereferences a NULL napi->dev.\n\nAllocate the dummy netdev and add the shared tx/rx NAPI to it before the\nregister_netdev() loop. Both the dummy-allocation failure and a\nregister_netdev() failure now unwind through mtk_unreg_dev(), which\nunregisters the net_device notifiers and the netdevs registered so far,\nstopping a concurrently-opened netdev (ndo_stop) and its NAPI before the\ndummy carrier is freed.\n\nA netdev that opened during the window can also have queued the\nframe-engine reset worker (via the tx watchdog or phylink), so the probe\nerror path now cancels eth->pending_work before freeing the shared state,\nas mtk_cleanup() already does on remove.\n\n## Affected\n\n- `Linux >= 656e705243fd0c2864b89634ea16ed444ef64dc6 < 42001839e425b2564b7297be579073a13a8fddf6`\n- `Linux >= 656e705243fd0c2864b89634ea16ed444ef64dc6 < 82be3d08de9e14d5aed72377f051adb4f09fd540`\n- `Linux >= 656e705243fd0c2864b89634ea16ed444ef64dc6 < 17eafd74de5a31e30361420a2e3ebf64186b77e5`\n- `Linux >= 656e705243fd0c2864b89634ea16ed444ef64dc6 < 6f0c2c4f5e7143eba75153ecc8af3a03f7b6a98b`\n- `Linux 4.6`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}