{"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"}}}}