{"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"}}}}