GHSA-G774-9RM3-MCQ6
Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-19 18:31In the Linux kernel, the following vulnerability has been resolved:
nvme-pci: fix use-after-free in nvme_free_host_mem()
nvme_free_host_mem() frees dev->hmb_sgt via dma_free_noncontiguous() but never clears the pointer afterward. This leads to a use-after-free if nvme_free_host_mem() is called twice in the same error path.
This can happen during nvme_probe() when nvme_setup_host_mem() succeeds in allocating the HMB (setting dev->hmb_sgt) but nvme_set_host_mem() fails with an I/O error:
nvme_setup_host_mem() nvme_alloc_host_mem_single() -> sets dev->hmb_sgt nvme_set_host_mem() -> fails with -EIO nvme_free_host_mem() -> frees hmb_sgt, but does NOT NULL it return error
nvme_probe() error path: nvme_free_host_mem() -> dev->hmb_sgt is stale, use-after-free
The second call dereferences the freed sgt, causing a NULL pointer dereference in iommu_dma_free_noncontiguous() when it accesses sgt->sgl->dma_address (the backing memory has been freed and zeroed).
This is reproducible on Thunderbolt-attached NVMe devices (e.g., OWC Envoy Express behind a Dell WD22TB4 dock) where the device intermittently returns I/O errors during HMB setup due to PCIe link instability.
BUG: kernel NULL pointer dereference, address: 0000000000000010 RIP: 0010:iommu_dma_free_noncontiguous+0x22/0x80 Call Trace: dma_free_noncontiguous+0x3b/0x130 nvme_free_host_mem+0x30/0xf0 [nvme] nvme_probe.cold+0xcc/0x275 [nvme] local_pci_probe+0x43/0xa0 pci_device_probe+0xeea/0x290 really_probe+0xf9/0x3b0 __driver_probe_device+0x8b/0x170 driver_probe_device+0x24/0xd0 __driver_attach_async_helper+0x6b/0x110 async_run_entry_fn+0x37/0x170 process_one_work+0x1ac/0x3d0 worker_thread+0x1b8/0x360 kthread+0xf7/0x130 ret_from_fork+0x2d8/0x3a0 ret_from_fork_asm+0x1a/0x30
Fix this by setting dev->hmb_sgt to NULL after freeing it, so the second call takes the multi-descriptor path which safely handles the already-cleaned-up state.
{
"affected": [],
"aliases": [
"CVE-2026-64071"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T16:17:47Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvme-pci: fix use-after-free in nvme_free_host_mem()\n\nnvme_free_host_mem() frees dev-\u003ehmb_sgt via dma_free_noncontiguous()\nbut never clears the pointer afterward. This leads to a use-after-free\nif nvme_free_host_mem() is called twice in the same error path.\n\nThis can happen during nvme_probe() when nvme_setup_host_mem() succeeds\nin allocating the HMB (setting dev-\u003ehmb_sgt) but nvme_set_host_mem()\nfails with an I/O error:\n\n nvme_setup_host_mem()\n nvme_alloc_host_mem_single() -\u003e sets dev-\u003ehmb_sgt\n nvme_set_host_mem() -\u003e fails with -EIO\n nvme_free_host_mem() -\u003e frees hmb_sgt, but does NOT NULL it\n return error\n\n nvme_probe() error path:\n nvme_free_host_mem() -\u003e dev-\u003ehmb_sgt is stale, use-after-free\n\nThe second call dereferences the freed sgt, causing a NULL pointer\ndereference in iommu_dma_free_noncontiguous() when it accesses\nsgt-\u003esgl-\u003edma_address (the backing memory has been freed and zeroed).\n\nThis is reproducible on Thunderbolt-attached NVMe devices (e.g., OWC\nEnvoy Express behind a Dell WD22TB4 dock) where the device intermittently\nreturns I/O errors during HMB setup due to PCIe link instability.\n\n BUG: kernel NULL pointer dereference, address: 0000000000000010\n RIP: 0010:iommu_dma_free_noncontiguous+0x22/0x80\n Call Trace:\n \u003cTASK\u003e\n dma_free_noncontiguous+0x3b/0x130\n nvme_free_host_mem+0x30/0xf0 [nvme]\n nvme_probe.cold+0xcc/0x275 [nvme]\n local_pci_probe+0x43/0xa0\n pci_device_probe+0xeea/0x290\n really_probe+0xf9/0x3b0\n __driver_probe_device+0x8b/0x170\n driver_probe_device+0x24/0xd0\n __driver_attach_async_helper+0x6b/0x110\n async_run_entry_fn+0x37/0x170\n process_one_work+0x1ac/0x3d0\n worker_thread+0x1b8/0x360\n kthread+0xf7/0x130\n ret_from_fork+0x2d8/0x3a0\n ret_from_fork_asm+0x1a/0x30\n \u003c/TASK\u003e\n\nFix this by setting dev-\u003ehmb_sgt to NULL after freeing it, so the\nsecond call takes the multi-descriptor path which safely handles the\nalready-cleaned-up state.",
"id": "GHSA-g774-9rm3-mcq6",
"modified": "2026-07-19T18:31:51Z",
"published": "2026-07-19T18:31:51Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64071"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7c89f474005d8377525d2991930b7432ee193a52"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9525e3a6fbb1d126a22ab2ee86ddea25af581a7c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b35a13036755c5803168a7cb93bc66035c3e65b8"
}
],
"schema_version": "1.4.0",
"severity": []
}
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