{"id":"CVE-2026-72343","summary":"net/mlx5e: Fix HV VHCA stats zero-sized buffer allocation","details":"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-\u003estats_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-\u003estats_agent.buf set to ZERO_SIZE_PTR.\n\nOnce channels are opened (priv-\u003estats_nch \u003e 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-\u003emax_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-\u003erings = 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-\u003estats_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-\u003estats_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-\u003echannel_stats) and lazily populating\nentries up to stats_nch on demand.","modified":"2026-08-16T03:48:37.396796576Z","published":"2026-08-15T05:55:49.067Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72343.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/22c1d5ecccf92c849bdca1556179aafc95794baf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/25f6b929c7e379cbea7cb8caa67b49b2d1efae17"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3b3a552cf88e10bb7bda88b29cf1fd8267043d50"},{"type":"WEB","url":"https://git.kernel.org/stable/c/420aabb32da4381d8d7cdcaa6a77fad9eaceb0a4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5b927dcec5f1087942bf123a82e64a3f66475f01"},{"type":"WEB","url":"https://git.kernel.org/stable/c/abc4c56427f144c96b2827a4db3b90eb5b7349a2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72343.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72343"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"fa691d0c9c0812b9045f3a9420862e47b3b92518"},{"fixed":"3b3a552cf88e10bb7bda88b29cf1fd8267043d50"},{"fixed":"5b927dcec5f1087942bf123a82e64a3f66475f01"},{"fixed":"22c1d5ecccf92c849bdca1556179aafc95794baf"},{"fixed":"420aabb32da4381d8d7cdcaa6a77fad9eaceb0a4"},{"fixed":"abc4c56427f144c96b2827a4db3b90eb5b7349a2"},{"fixed":"25f6b929c7e379cbea7cb8caa67b49b2d1efae17"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72343.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.17.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72343.json"}}],"schema_version":"1.9.0"}