243 lines
14 KiB
JSON
243 lines
14 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-93830",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-09-18T17:59:28.793Z",
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"datePublished": "2026-09-24T16:03:12.818Z",
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"dateUpdated": "2026-10-03T10:58:00.189Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-03T10:58:00.189Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: xgmac2: disable RBUE in default RX interrupt mask\n\nEnabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive\nand can trigger a MAC interrupt storm under heavy RX pressure. When the\nDMA runs out of RX descriptors it fires RBUE continuously until software\nrefills the ring.\n\nHowever, RBUE is redundant: the normal RX completion interrupt (RIE)\nalready triggers NAPI, which processes completed descriptors and refills\nthe ring, causing the DMA to resume. The RBUE handler itself only sets\nhandle_rx - the same outcome as RIE.\n\nOn Agilex5 under heavy RX pressure, the MAC interrupt (which includes\nRBUE) was observed firing 1,821,811,555 times against only 2,618,627\nactual RX completions - a ~695x ratio - confirming the severity of the\nstorm.\n\nRBUE does not provide OOM recovery. If page_pool is exhausted,\nstmmac_rx_refill() cannot advance the DMA tail pointer, the DMA stays\nsuspended, and RBUE fires again on the next NAPI completion - a storm\nwith no forward progress. This patch trades that storm for a clean\nstall with the same RX outcome. Proper OOM recovery is a pre-existing\ngap outside the scope of this fix.\n\nNote: as a consequence of disabling RBUE, the rx_buf_unav_irq ethtool\ncounter will always read 0 on XGMAC2 devices. This behaviour is already\ninconsistent across DWMAC core versions.\n\nRemove RBUE from XGMAC_DMA_INT_DEFAULT_EN and XGMAC_DMA_INT_DEFAULT_RX\nto prevent the interrupt storm while keeping normal RX handling intact."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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"baseScore": 7.5,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:N - Inbound Ethernet frames (IPv4/IPv6 unicast to the host MAC) are DMA'd into the XGMAC2 RX ring; emptying it asserts XGMAC_RBU. With XGMAC_RBUE in XGMAC_DMA_INT_DEFAULT_RX, stmmac_interrupt/stmmac_msi_intr_rx → stmmac_napi_check → dwxgmac2_dma_interrupt runs. XGMAC2 is a 10G IP Ethernet MAC (Agilex5, Tegra MGBE, snps,dwxgmac).\nAC:L - A remote flood is enough: DMA_DEFAULT_RX_SIZE is 512, and Agilex5 under heavy RX already produced 1,821,811,555 MAC IRQs versus 2,618,627 completions. The attacker sets arrival rate; no race or layout is required. The worse stall (page_pool_alloc_pages failure in stmmac_rx_refill) is also GFP_ATOMIC exhaustion from that flood.\nPR:N - dwxgmac2_dma_interrupt runs from the XGMAC DMA hardirq (stmmac_interrupt or stmmac_msi_intr_rx) on received frames before any socket, netfilter verdict, or authentication check.\nUI:N - The attacker sends the frames themselves; stmmac_interrupt/stmmac_msi_intr_rx schedules NAPI via stmmac_napi_check with no local user action.\nS:U - The RBUE storm runs in the host kernel ISR/NAPI (stmmac_interrupt, dwxgmac2_dma_interrupt, stmmac_napi_poll_rx); it does not cross a VM, IOMMU, or sandbox boundary.\nC:N - On XGMAC_RBU, dwxgmac2_dma_interrupt only increments x->rx_buf_unav_irq and returns handle_rx so NAPI runs; it does not read or return kernel memory to the sender.\nI:N - The RBU handler does not write attacker-controlled data into kernel objects; it only sets handle_rx. There is no OOB write, UAF, or control-flow hijack.\nA:H - With XGMAC_RBUE armed, RBU reasserts until stmmac_rx_refill advances the RX tail; if page_pool_alloc_pages fails, stmmac_napi_poll_rx's napi_complete_done path calls dwxgmac2_enable_dma_irq and the IRQ storms with no forward progress (~695x on Agilex5), livelocking the CPU."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h"
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],
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"versions": [
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{
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"version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
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"lessThan": "8c9d57b5dc098b84631d0b3559c84c499ea2170a",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
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"lessThan": "7a10e54e42a8f73a8d731f5a281fc06bb41b9250",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
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"lessThan": "6b3b91433d5f4eae6865cdaa96f40cd67849e1f6",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
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"lessThan": "74dbb85a6a254b5fc1f265a6cd61b2ba9d9221d7",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
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"lessThan": "0b1a5d3647ce07c27a9fffefc11a8cbf7d7b25ce",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
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"lessThan": "87e2826ed2058747ddf014c082569a46bfadd96b",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
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"lessThan": "d3265c19b35d036bba327b36b5366bee76b0157c",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h"
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],
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"versions": [
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{
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"version": "4.19",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "4.19",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.10.271",
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"lessThanOrEqual": "5.10.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.15.222",
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"lessThanOrEqual": "5.15.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.1.189",
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"lessThanOrEqual": "6.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.158",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.111",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.53",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "4.19",
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"versionEndExcluding": "5.10.271"
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]
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/8c9d57b5dc098b84631d0b3559c84c499ea2170a"
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},
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{
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"url": "https://git.kernel.org/stable/c/7a10e54e42a8f73a8d731f5a281fc06bb41b9250"
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},
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{
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"url": "https://git.kernel.org/stable/c/6b3b91433d5f4eae6865cdaa96f40cd67849e1f6"
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},
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{
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"url": "https://git.kernel.org/stable/c/74dbb85a6a254b5fc1f265a6cd61b2ba9d9221d7"
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},
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{
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"url": "https://git.kernel.org/stable/c/0b1a5d3647ce07c27a9fffefc11a8cbf7d7b25ce"
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},
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{
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"url": "https://git.kernel.org/stable/c/87e2826ed2058747ddf014c082569a46bfadd96b"
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},
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{
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"url": "https://git.kernel.org/stable/c/d3265c19b35d036bba327b36b5366bee76b0157c"
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}
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],
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"title": "net: stmmac: xgmac2: disable RBUE in default RX interrupt mask",
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"x_generator": {
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"engine": "bippy-1.2.0"
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} |