CVE-2026-72343 (GCVE-0-2026-72343)
Vulnerability from cvelistv5
Published
2026-08-15 05:55
Modified
2026-08-17 05:43
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Fix HV VHCA stats zero-sized buffer allocation
mlx5e_hv_vhca_stats_create() is called from mlx5e_nic_enable(),
before mlx5e_open(). At that point priv->stats_nch is still zero,
because it is only ever incremented in mlx5e_channel_stats_alloc(),
which is reached only from mlx5e_open_channel().
mlx5e_hv_vhca_stats_buf_size() therefore returns 0, and
kvzalloc(0, GFP_KERNEL) returns ZERO_SIZE_PTR ((void *)16) rather
than NULL. The "if (!buf)" guard does not catch this, and
mlx5e_hv_vhca_stats_create() completes "successfully" with
priv->stats_agent.buf set to ZERO_SIZE_PTR.
Once channels are opened (priv->stats_nch > 0) and the hypervisor
enables stats reporting, mlx5e_hv_vhca_stats_work() recomputes
buf_len using the new non-zero stats_nch and calls
memset(buf, 0, buf_len) on ZERO_SIZE_PTR, faulting at address 0x10.
Allocate the buffer based on priv->max_nch, which is set in
mlx5e_priv_init() and is the upper bound on stats_nch:
- Add a separate helper mlx5e_hv_vhca_stats_buf_max_size() that
returns sizeof(per_ring_stats) * max(max_nch, stats_nch), and
use it for the kvzalloc() in mlx5e_hv_vhca_stats_create().
- Keep mlx5e_hv_vhca_stats_buf_size() (which returns based on
stats_nch) for the worker's active payload size, so the wire
format (block->rings = stats_nch) and the amount of data filled
by mlx5e_hv_vhca_fill_stats() are unchanged.
The max(max_nch, stats_nch) guard handles the rare case where
mlx5e_attach_netdev() recomputes max_nch downward across a
detach/resume cycle while priv->stats_nch persists (mlx5e_detach_netdev
does not call mlx5e_priv_cleanup, so stats_nch is only reset when
the netdev is destroyed). Without the guard, the worker could compute
buf_len from stats_nch and overrun the smaller buffer allocated based
on the reduced max_nch.
Allocating a non-zero buffer also makes the kvzalloc() failure path in
mlx5e_hv_vhca_stats_create() reachable for the first time: it returns
early without (re)creating the agent. Clear
priv->stats_agent.{agent,buf} in mlx5e_hv_vhca_stats_destroy() after
freeing them, so that if a later create() bails out on this path, a
subsequent teardown does not double-free the stale agent/buffer left
from a previous enable/disable cycle.
This mirrors the existing mlx5e pattern of preallocating arrays of
size max_nch (e.g. priv->channel_stats) and lazily populating
entries up to stats_nch on demand.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: fa691d0c9c0812b9045f3a9420862e47b3b92518 Version: fa691d0c9c0812b9045f3a9420862e47b3b92518 Version: fa691d0c9c0812b9045f3a9420862e47b3b92518 Version: fa691d0c9c0812b9045f3a9420862e47b3b92518 Version: fa691d0c9c0812b9045f3a9420862e47b3b92518 Version: fa691d0c9c0812b9045f3a9420862e47b3b92518 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/net/ethernet/mellanox/mlx5/core/en/hv_vhca_stats.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "3b3a552cf88e10bb7bda88b29cf1fd8267043d50",
"status": "affected",
"version": "fa691d0c9c0812b9045f3a9420862e47b3b92518",
"versionType": "git"
},
{
"lessThan": "5b927dcec5f1087942bf123a82e64a3f66475f01",
"status": "affected",
"version": "fa691d0c9c0812b9045f3a9420862e47b3b92518",
"versionType": "git"
},
{
"lessThan": "22c1d5ecccf92c849bdca1556179aafc95794baf",
"status": "affected",
"version": "fa691d0c9c0812b9045f3a9420862e47b3b92518",
"versionType": "git"
},
{
"lessThan": "420aabb32da4381d8d7cdcaa6a77fad9eaceb0a4",
"status": "affected",
"version": "fa691d0c9c0812b9045f3a9420862e47b3b92518",
"versionType": "git"
},
{
"lessThan": "abc4c56427f144c96b2827a4db3b90eb5b7349a2",
"status": "affected",
"version": "fa691d0c9c0812b9045f3a9420862e47b3b92518",
"versionType": "git"
},
{
"lessThan": "25f6b929c7e379cbea7cb8caa67b49b2d1efae17",
"status": "affected",
"version": "fa691d0c9c0812b9045f3a9420862e47b3b92518",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/net/ethernet/mellanox/mlx5/core/en/hv_vhca_stats.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.17"
},
{
"lessThan": "5.17",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.178",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.145",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.97",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.40",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.5",
"versionStartIncluding": "5.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "5.17",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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-\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\u0027s 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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.4,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"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\u003e0 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."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:43:01.870Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"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"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-72343",
"datePublished": "2026-08-15T05:55:49.067Z",
"dateReserved": "2026-08-09T03:40:39.920Z",
"dateUpdated": "2026-08-17T05:43:01.870Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…