{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72343", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.920Z", "datePublished": "2026-08-15T05:55:49.067Z", "dateUpdated": "2026-08-17T05:43:01.870Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:43:01.870Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: Fix HV VHCA stats zero-sized buffer allocation\n\nmlx5e_hv_vhca_stats_create() is called from mlx5e_nic_enable(),\nbefore mlx5e_open(). At that point priv->stats_nch is still zero,\nbecause it is only ever incremented in mlx5e_channel_stats_alloc(),\nwhich is reached only from mlx5e_open_channel().\n\nmlx5e_hv_vhca_stats_buf_size() therefore returns 0, and\nkvzalloc(0, GFP_KERNEL) returns ZERO_SIZE_PTR ((void *)16) rather\nthan NULL. The \"if (!buf)\" guard does not catch this, and\nmlx5e_hv_vhca_stats_create() completes \"successfully\" with\npriv->stats_agent.buf set to ZERO_SIZE_PTR.\n\nOnce channels are opened (priv->stats_nch > 0) and the hypervisor\nenables stats reporting, mlx5e_hv_vhca_stats_work() recomputes\nbuf_len using the new non-zero stats_nch and calls\nmemset(buf, 0, buf_len) on ZERO_SIZE_PTR, faulting at address 0x10.\n\nAllocate the buffer based on priv->max_nch, which is set in\nmlx5e_priv_init() and is the upper bound on stats_nch:\n\n - Add a separate helper mlx5e_hv_vhca_stats_buf_max_size() that\n returns sizeof(per_ring_stats) * max(max_nch, stats_nch), and\n use it for the kvzalloc() in mlx5e_hv_vhca_stats_create().\n - Keep mlx5e_hv_vhca_stats_buf_size() (which returns based on\n stats_nch) for the worker's active payload size, so the wire\n format (block->rings = stats_nch) and the amount of data filled\n by mlx5e_hv_vhca_fill_stats() are unchanged.\n\nThe max(max_nch, stats_nch) guard handles the rare case where\nmlx5e_attach_netdev() recomputes max_nch downward across a\ndetach/resume cycle while priv->stats_nch persists (mlx5e_detach_netdev\ndoes not call mlx5e_priv_cleanup, so stats_nch is only reset when\nthe netdev is destroyed). Without the guard, the worker could compute\nbuf_len from stats_nch and overrun the smaller buffer allocated based\non the reduced max_nch.\n\nAllocating a non-zero buffer also makes the kvzalloc() failure path in\nmlx5e_hv_vhca_stats_create() reachable for the first time: it returns\nearly without (re)creating the agent. Clear\npriv->stats_agent.{agent,buf} in mlx5e_hv_vhca_stats_destroy() after\nfreeing them, so that if a later create() bails out on this path, a\nsubsequent teardown does not double-free the stale agent/buffer left\nfrom a previous enable/disable cycle.\n\nThis mirrors the existing mlx5e pattern of preallocating arrays of\nsize max_nch (e.g. priv->channel_stats) and lazily populating\nentries up to stats_nch on demand." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.4, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The flaw is reached via the Hyper-V VMBus PCI config back-channel (PCI_INVALIDATE_BLOCK) into mlx5e HV VHCA stats handling during mlx5e driver operation on Azure mlx5 NICs, not via remote network packets or guest syscall/ioctl paths.\nAC:L - mlx5e_nic_enable always calls mlx5e_hv_vhca_stats_create before mlx5e_open, so kvzalloc(0) deterministically stores ZERO_SIZE_PTR; once channels open and the hypervisor enables stats reporting, the worker always memset()s with buf_len>0 and faults.\nPR:N - On Azure/Hyper-V mlx5 VMs the host routinely drives VHCA stats collection over the PCI config back-channel during normal operation; no guest credentials, CAP_NET_ADMIN, or other elevated guest privileges are required beyond standard VM boot with the NIC active.\nUI:N - Triggering requires only normal VM boot and mlx5e driver bring-up with channels opened; no victim file open, mount, or other interactive administrator action is needed to reach the faulty memset path.\nS:U - Kernel memory corruption and panic are confined to the guest kernel running mlx5e on the affected VM; the bug does not cross VM/host, IOMMU, or other security boundaries into a separate authority.\nC:H - memset(buf,0,buf_len) on ZERO_SIZE_PTR is an out-of-bounds write from a near-NULL kernel address; per kernel guidance any such memory corruption can be leveraged for information disclosure even though the immediate operation writes zeros.\nI:H - The worker performs a large out-of-bounds write via memset on the bogus buffer pointer, and the pre-fix sizing logic can also overrun a too-small allocation when stats_nch exceeds max_nch after detach/resume, enabling arbitrary kernel write primitives.\nA:H - The memset on ZERO_SIZE_PTR faults at address 0x10 causing a kernel oops or panic, reliably denying availability of Azure/Hyper-V guests using CONFIG_PCI_HYPERV_INTERFACE mlx5 NICs whenever the hypervisor enables stats reporting." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/mellanox/mlx5/core/en/hv_vhca_stats.c" ], "versions": [ { "version": "fa691d0c9c0812b9045f3a9420862e47b3b92518", "lessThan": "3b3a552cf88e10bb7bda88b29cf1fd8267043d50", "status": "affected", "versionType": "git" }, { "version": "fa691d0c9c0812b9045f3a9420862e47b3b92518", "lessThan": "5b927dcec5f1087942bf123a82e64a3f66475f01", "status": "affected", "versionType": "git" }, { "version": "fa691d0c9c0812b9045f3a9420862e47b3b92518", "lessThan": "22c1d5ecccf92c849bdca1556179aafc95794baf", "status": "affected", "versionType": "git" }, { "version": "fa691d0c9c0812b9045f3a9420862e47b3b92518", "lessThan": "420aabb32da4381d8d7cdcaa6a77fad9eaceb0a4", "status": "affected", "versionType": "git" }, { "version": "fa691d0c9c0812b9045f3a9420862e47b3b92518", "lessThan": "abc4c56427f144c96b2827a4db3b90eb5b7349a2", "status": "affected", "versionType": "git" }, { "version": "fa691d0c9c0812b9045f3a9420862e47b3b92518", "lessThan": "25f6b929c7e379cbea7cb8caa67b49b2d1efae17", "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/mellanox/mlx5/core/en/hv_vhca_stats.c" ], "versions": [ { "version": "5.17", "status": "affected" }, { "version": "0", "lessThan": "5.17", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "5.17", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3b3a552cf88e10bb7bda88b29cf1fd8267043d50" }, { "url": "https://git.kernel.org/stable/c/5b927dcec5f1087942bf123a82e64a3f66475f01" }, { "url": "https://git.kernel.org/stable/c/22c1d5ecccf92c849bdca1556179aafc95794baf" }, { "url": "https://git.kernel.org/stable/c/420aabb32da4381d8d7cdcaa6a77fad9eaceb0a4" }, { "url": "https://git.kernel.org/stable/c/abc4c56427f144c96b2827a4db3b90eb5b7349a2" }, { "url": "https://git.kernel.org/stable/c/25f6b929c7e379cbea7cb8caa67b49b2d1efae17" } ], "title": "net/mlx5e: Fix HV VHCA stats zero-sized buffer allocation", "x_generator": { "engine": "bippy-1.2.0" } } } }