{"id":"CVE-2026-72343","title":"net/mlx5e: Fix HV VHCA stats zero-sized buffer allocation","summary":"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->stat…","severity":"high","cvss":8.4,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 3b3a552cf88e10bb7bda88b29cf1fd8267043d50","Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 5b927dcec5f1087942bf123a82e64a3f66475f01","Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 22c1d5ecccf92c849bdca1556179aafc95794baf","Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 420aabb32da4381d8d7cdcaa6a77fad9eaceb0a4","Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < abc4c56427f144c96b2827a4db3b90eb5b7349a2","Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 25f6b929c7e379cbea7cb8caa67b49b2d1efae17","Linux 5.17"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:47:27.911356Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:19.281Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72343","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"}],"tags":["cve.org"],"epss":0.00196,"epssPercentile":0.08643,"ingestedAt":"2026-10-16T19:46:24.406Z","slug":"CVE-2026-72343","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 3b3a552cf88e10bb7bda88b29cf1fd8267043d50`\n- `Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 5b927dcec5f1087942bf123a82e64a3f66475f01`\n- `Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 22c1d5ecccf92c849bdca1556179aafc95794baf`\n- `Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 420aabb32da4381d8d7cdcaa6a77fad9eaceb0a4`\n- `Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < abc4c56427f144c96b2827a4db3b90eb5b7349a2`\n- `Linux >= fa691d0c9c0812b9045f3a9420862e47b3b92518 < 25f6b929c7e379cbea7cb8caa67b49b2d1efae17`\n- `Linux 5.17`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":46,"depthScoreParts":{"impact":46.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}