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CVE-2026-99081— bnxt_en: fix DMA mapping length for padded small packets

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： bnxt_en：修复带填充的小数据包的 DMA 映射长度 Stefan Fleischmann 报告称，在 BCM57412 NetXtreme-E 网卡上通过 VLAN/macvlan 接口发送数据包时，Intel IOMMU 会触发 DMA 读错误： 错误地址（0xfc499000）恰好位于 4KB 页边界，表明发生了 DMA 读缓冲区溢出。 在 函数中，小于 （52 字节）的数据包（例如 42 字节的未标记 ARP 帧）会被填充： 然而，变量 在之前已被初始化为

AI Predicted 7.5 Difficulty: Moderate

Possible ATT&CK Techniques 1 AI

T1069 · Permission Groups Discovery

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux c0c050c58d840994ba842ad1c338a98e7c12b764< cf8530a25ae92c4493e2f22981ecb46f0b66f4c8 affected
c0c050c58d840994ba842ad1c338a98e7c12b764< 2956aca14dd2977cd08bd2ccafae3beb8b84b268 affected
c0c050c58d840994ba842ad1c338a98e7c12b764< fbd977e513971ccb4f0762a7f59eac500e474f89 affected
c0c050c58d840994ba842ad1c338a98e7c12b764< 5213f65a9667d3dd85db2e6df8f2e0516290db34 affected
c0c050c58d840994ba842ad1c338a98e7c12b764< a51d233ccd4889aadb71dace863525cc2b00271e affected
4.4 affected
< 4.4 unaffected
6.6.160≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-99081

Vulnerability Information
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Vulnerability Title
bnxt_en: fix DMA mapping length for padded small packets
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: bnxt_en: fix DMA mapping length for padded small packets Stefan Fleischmann reported Intel IOMMU DMA Read faults on BCM57412 NetXtreme-E NICs when transmitting packets on VLAN/macvlan interfaces: DMAR: [DMA Read NO_PASID] Request device [18:00.0] fault addr 0xfc499000 [fault reason 0x06] PTE Read access is not set bnxt_en 0000:18:00.0 eno1np0: Abandoning msg {0xb4 0x41a} len: 0 due to firmware status: 0x2000001 ... NETDEV WATCHDOG: eno1np0 (bnxt_en): transmit queue 0 timed out The fault address (0xfc499000) is on an exact 4KB page boundary, pointing to a DMA read buffer overrun. In bnxt_start_xmit(), packets smaller than BNXT_MIN_PKT_SIZE (52 bytes), such as 42-byte untagged ARP frames, are padded: if (length < BNXT_MIN_PKT_SIZE) { pad = BNXT_MIN_PKT_SIZE - length; if (skb_pad(skb, pad)) goto tx_kick_pending; length = BNXT_MIN_PKT_SIZE; } mapping = dma_map_single(&pdev->dev, skb->data, len, DMA_TO_DEVICE); ... dma_unmap_len_set(tx_buf, len, len); However, 'len' was initialized earlier to skb_headlen(skb) (e.g. 42 bytes) and is left unadjusted after padding. Consequently, dma_map_single() and dma_unmap_len_set() map and track only 42 bytes. Later, the hardware TX buffer descriptor is programmed with the padded length: txbd->tx_bd_len_flags_type = cpu_to_le32(((len + pad) << TX_BD_LEN_SHIFT) | flags | TX_BD_FLAGS_PACKET_END); The NIC DMA engine is thus instructed to read 52 bytes from a region where only 42 bytes were DMA-mapped. If skb->data ends near the boundary of a 4KB page (within 'pad' bytes of the next page), the hardware DMA read overruns into the unmapped adjacent page, triggering an IOMMU fault. This issue was exposed after commit 447cbe95ebb9 ("vlan: fix skb_under_panic and races when toggling HW VLAN offload") because reserving extra VLAN headroom rounded LL_RESERVED_SPACE from 48 up to 64 bytes, shifting skb->data offsets and potentially causing small frames to land right against page boundaries. Fix this by using skb_put_padto(skb, BNXT_MIN_PKT_SIZE) in bnxt_start_xmit(), before skb_shinfo(skb)->nr_frags is sampled, because padding might linearize the skb. This ensures skb->len and skb_headlen(skb) reflect the padded size so that dma_map_single() maps the full buffer and the descriptor length is consistent. This also removes the temporary 'pad' variable and masking logic. The padding is done after the SW USO branch, otherwise bnxt_sw_udp_gso_xmit() would account the padding as UDP payload and send it in extra segments. Note that SW USO segments are still not padded: with IPv4, a segment carrying less than 10 bytes of UDP payload (small gso_size, or a short last segment) is sent as a frame shorter than BNXT_MIN_PKT_SIZE. This is a separate issue, left for a followup patch.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux c0c050c58d840994ba842ad1c338a98e7c12b764 ~ cf8530a25ae92c4493e2f22981ecb46f0b66f4c8 -
Linux Linux 4.4 -

II. Public POCs for CVE-2026-99081

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III. Intelligence Information for CVE-2026-99081

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Patches & Fixes for CVE-2026-99081 (4)

Same Patch Batch · Linux · 2026-10-23 · 218 CVEs total

CVE-2026-98937 perf/core: Check kernel access when kernel callchains are requested
CVE-2026-98950 flow_dissector: avoid u16 truncation of hlen in bpf_flow_dissect()
CVE-2026-98949 drm/imagination: Fix reference and vm_bo handling in remap()
CVE-2026-98948 mlxsw: spectrum_flower: Fix port range register leak in tmplt_create()
CVE-2026-98947 vsock: Fix memory leak in vmci_transport_recv_dgram_cb()
CVE-2026-98946 drm/vc4: Disable the V3D interrupt across runtime suspend
CVE-2026-98945 HID: steam: Rearrange teardown sequence
CVE-2026-98944 HID: steam: Refactor registration
CVE-2026-98943 HID: steam: Clean up locking
CVE-2026-98942 sched_ext: Build the cid tables privately and publish them with RCU
CVE-2026-98941 ext4: don't enable large folios on encrypted inodes
CVE-2026-98940 ASoC: qcom: lpass-cpu: use DAI table index for playback constraints
CVE-2026-98939 x86/mm: Drop unnecessary PMD page copy when freeing
CVE-2026-98938 rust: irq: pass RegistrationInner as cookie to request_irq
CVE-2026-98926 drm/amd/display: Remove sink usage from DPMS
CVE-2026-98929 macsec: initialize SecY before registering the netdevice
CVE-2026-98928 KVM: arm64: Derive GUEST_HAS_SVE from the SVE feature bit at EL2
CVE-2026-98927 KVM: arm64: nv: Fix life cycle of the nested_mmus array
CVE-2026-98930 KVM: s390: Fix IRQ injection with SIGP Stop and Store Status
CVE-2026-98925 bpf, sockmap: Fix self-redirect copied_seq double-counting

Showing top 20 of 218 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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