{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-99081", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.390Z", "datePublished": "2026-10-23T12:23:28.347Z", "dateUpdated": "2026-10-30T12:41:36.421Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-30T12:41:36.421Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbnxt_en: fix DMA mapping length for padded small packets\n\nStefan Fleischmann reported Intel IOMMU DMA Read faults on BCM57412\nNetXtreme-E NICs when transmitting packets on VLAN/macvlan interfaces:\n\n DMAR: [DMA Read NO_PASID] Request device [18:00.0] fault addr 0xfc499000\n [fault reason 0x06] PTE Read access is not set\n bnxt_en 0000:18:00.0 eno1np0: Abandoning msg {0xb4 0x41a} len: 0 due to firmware status: 0x2000001\n ...\n NETDEV WATCHDOG: eno1np0 (bnxt_en): transmit queue 0 timed out\n\nThe fault address (0xfc499000) is on an exact 4KB page boundary,\npointing to a DMA read buffer overrun.\n\nIn bnxt_start_xmit(), packets smaller than BNXT_MIN_PKT_SIZE (52 bytes),\nsuch as 42-byte untagged ARP frames, are padded:\n\n if (length < BNXT_MIN_PKT_SIZE) {\n pad = BNXT_MIN_PKT_SIZE - length;\n if (skb_pad(skb, pad))\n goto tx_kick_pending;\n length = BNXT_MIN_PKT_SIZE;\n }\n\n mapping = dma_map_single(&pdev->dev, skb->data, len, DMA_TO_DEVICE);\n ...\n dma_unmap_len_set(tx_buf, len, len);\n\nHowever, 'len' was initialized earlier to skb_headlen(skb) (e.g. 42 bytes)\nand is left unadjusted after padding. Consequently, dma_map_single() and\ndma_unmap_len_set() map and track only 42 bytes.\n\nLater, the hardware TX buffer descriptor is programmed with the padded length:\n\n txbd->tx_bd_len_flags_type =\n cpu_to_le32(((len + pad) << TX_BD_LEN_SHIFT) | flags |\n TX_BD_FLAGS_PACKET_END);\n\nThe NIC DMA engine is thus instructed to read 52 bytes from a region where\nonly 42 bytes were DMA-mapped. If skb->data ends near the boundary of a 4KB\npage (within 'pad' bytes of the next page), the hardware DMA read overruns\ninto the unmapped adjacent page, triggering an IOMMU fault.\n\nThis issue was exposed after commit 447cbe95ebb9 (\"vlan: fix skb_under_panic\nand races when toggling HW VLAN offload\") because reserving extra VLAN\nheadroom rounded LL_RESERVED_SPACE from 48 up to 64 bytes, shifting skb->data\noffsets and potentially causing small frames to land right against page\nboundaries.\n\nFix this by using skb_put_padto(skb, BNXT_MIN_PKT_SIZE) in\nbnxt_start_xmit(), before skb_shinfo(skb)->nr_frags is sampled,\nbecause padding might linearize the skb.\nThis ensures skb->len and skb_headlen(skb) reflect the padded size so\nthat dma_map_single() maps the full buffer and the descriptor length is\nconsistent. This also removes the temporary 'pad' variable and masking logic.\n\nThe padding is done after the SW USO branch, otherwise\nbnxt_sw_udp_gso_xmit() would account the padding as UDP payload\nand send it in extra segments.\n\nNote that SW USO segments are still not padded: with IPv4, a segment\ncarrying less than 10 bytes of UDP payload (small gso_size, or a short\nlast segment) is sent as a frame shorter than BNXT_MIN_PKT_SIZE.\nThis is a separate issue, left for a followup patch." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - A minimal IPv4 ICMP Echo Request follows bnxt_poll→bnxt_rx_pkt→icmp_rcv→icmp_echo; icmp_reply builds a 42-byte reply that reaches the patched bnxt_start_xmit through ip_finish_output2→dev_queue_xmit, including vlan_dev_hard_start_xmit on the reported VLAN setup.\nAC:L - A request burst keeps the TX ring nonempty, bypassing the push fast path and repeatedly exercising the 42-to-52-byte mismatch; repeated skb allocations provide the documented 4-KiB boundary placement without a race, second actor, or hardware failure.\nPR:N - icmp_rcv and icmp_echo process the Echo Request and invoke icmp_reply without socket credentials, capability checks, or authentication, so the remote sender needs no account or privileges.\nUI:N - Receipt of the ICMP Echo Request automatically constructs and transmits the short reply through bnxt_start_xmit; no victim must open a file, run a command, or otherwise act.\nS:U - bnxt_start_xmit misprograms the host NIC's TX DMA length, but the IOMMU rejects the overrun rather than being bypassed; no guest, sandbox, or other security authority is crossed.\nC:N - skb_pad zero-fills the intended ten padding bytes, while the demonstrated access reaches an unmapped IOVA page and faults; the code provides no path that returns host memory to the routed ICMP peer.\nI:N - The erroneous operation is a DMA_TO_DEVICE read of up to ten bytes beyond the mapping; it neither authorizes a NIC write into host memory nor modifies kernel data.\nA:H - The 52-byte descriptor read from a 42-byte mapping causes the documented IOMMU fault and NETDEV WATCHDOG TX-queue timeout; bnxt_tx_timeout then schedules bnxt_reset_task to close and reopen the NIC, and repeated requests can continually disrupt all interface traffic." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/broadcom/bnxt/bnxt.c" ], "versions": [ { "version": "c0c050c58d840994ba842ad1c338a98e7c12b764", "lessThan": "0f347e00d060dc0bf3b2d0ee041206e54848c233", "status": "affected", "versionType": "git" }, { "version": "c0c050c58d840994ba842ad1c338a98e7c12b764", "lessThan": "b3fd0177cf18a6ac98d41af80b4040010ea40f4d", "status": "affected", "versionType": "git" }, { "version": "c0c050c58d840994ba842ad1c338a98e7c12b764", "lessThan": "3a5d8465e73aff3c7d1ec38261dcaaa317367467", "status": "affected", "versionType": "git" }, { "version": "c0c050c58d840994ba842ad1c338a98e7c12b764", "lessThan": "cf8530a25ae92c4493e2f22981ecb46f0b66f4c8", "status": "affected", "versionType": "git" }, { "version": "c0c050c58d840994ba842ad1c338a98e7c12b764", "lessThan": "2956aca14dd2977cd08bd2ccafae3beb8b84b268", "status": "affected", "versionType": "git" }, { "version": "c0c050c58d840994ba842ad1c338a98e7c12b764", "lessThan": "fbd977e513971ccb4f0762a7f59eac500e474f89", "status": "affected", "versionType": "git" }, { "version": "c0c050c58d840994ba842ad1c338a98e7c12b764", "lessThan": "5213f65a9667d3dd85db2e6df8f2e0516290db34", "status": "affected", "versionType": "git" }, { "version": "c0c050c58d840994ba842ad1c338a98e7c12b764", "lessThan": "a51d233ccd4889aadb71dace863525cc2b00271e", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/broadcom/bnxt/bnxt.c" ], "versions": [ { "version": "4.4", "status": "affected" }, { "version": "0", "lessThan": "4.4", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.273", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.224", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.191", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.113", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.57", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.11", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "5.10.273" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "5.15.224" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.1.191" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.12.113" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.18.57" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "7.2.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0f347e00d060dc0bf3b2d0ee041206e54848c233" }, { "url": "https://git.kernel.org/stable/c/b3fd0177cf18a6ac98d41af80b4040010ea40f4d" }, { "url": "https://git.kernel.org/stable/c/3a5d8465e73aff3c7d1ec38261dcaaa317367467" }, { "url": "https://git.kernel.org/stable/c/cf8530a25ae92c4493e2f22981ecb46f0b66f4c8" }, { "url": "https://git.kernel.org/stable/c/2956aca14dd2977cd08bd2ccafae3beb8b84b268" }, { "url": "https://git.kernel.org/stable/c/fbd977e513971ccb4f0762a7f59eac500e474f89" }, { "url": "https://git.kernel.org/stable/c/5213f65a9667d3dd85db2e6df8f2e0516290db34" }, { "url": "https://git.kernel.org/stable/c/a51d233ccd4889aadb71dace863525cc2b00271e" } ], "title": "bnxt_en: fix DMA mapping length for padded small packets", "x_generator": { "engine": "bippy-1.2.0" } } } }