GHSA-GQWV-4RWR-X42G
Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-25 12:31In the Linux kernel, the following vulnerability has been resolved:
virtio_pci: fix vq info pointer lookup via wrong index
Unbinding a virtio balloon device:
echo virtio0 > /sys/bus/virtio/drivers/virtio_balloon/unbind
triggers a NULL pointer dereference. The dmesg says:
BUG: kernel NULL pointer dereference, address: 0000000000000008
[...]
RIP: 0010:__list_del_entry_valid_or_report+0x5/0xf0
Call Trace:
<TASK>
vp_del_vqs+0x121/0x230
remove_common+0x135/0x150
virtballoon_remove+0xee/0x100
virtio_dev_remove+0x3b/0x80
device_release_driver_internal+0x187/0x2c0
unbind_store+0xb9/0xe0
kernfs_fop_write_iter.llvm.11660790530567441834+0xf6/0x180
vfs_write+0x2a9/0x3b0
ksys_write+0x5c/0xd0
do_syscall_64+0x54/0x230
entry_SYSCALL_64_after_hwframe+0x29/0x31
[...]
</TASK>
The virtio_balloon device registers 5 queues (inflate, deflate, stats, free_page, reporting) but only the first two are unconditional. The stats, free_page and reporting queues are each conditional on their respective feature bits. When any of these features are absent, the corresponding vqs_info entry has name == NULL, creating holes in the array.
The root cause is an indexing mismatch introduced when vq info storage was changed to be passed as an argument. vp_find_vqs_msix() and vp_find_vqs_intx() store the info pointer at vp_dev->vqs[i], where 'i' is the caller's sparse array index. However, the virtqueue itself gets vq->index assigned from queue_idx, a dense index that skips NULL entries. When holes exist, 'i' and queue_idx diverge. Later, vp_del_vqs() looks up info via vp_dev->vqs[vq->index] using the dense index into the sparsely-populated array, and hits NULL.
Fix this by storing info at vp_dev->vqs[queue_idx] instead of vp_dev->vqs[i], so the store index matches the lookup index (vq->index). Apply the fix to both the MSIX and INTX paths.
{
"affected": [],
"aliases": [
"CVE-2026-64457"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-25T10:17:30Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirtio_pci: fix vq info pointer lookup via wrong index\n\nUnbinding a virtio balloon device:\n\n echo virtio0 \u003e /sys/bus/virtio/drivers/virtio_balloon/unbind\n\ntriggers a NULL pointer dereference. The dmesg says:\n\n BUG: kernel NULL pointer dereference, address: 0000000000000008\n [...]\n RIP: 0010:__list_del_entry_valid_or_report+0x5/0xf0\n Call Trace:\n \u003cTASK\u003e\n vp_del_vqs+0x121/0x230\n remove_common+0x135/0x150\n virtballoon_remove+0xee/0x100\n virtio_dev_remove+0x3b/0x80\n device_release_driver_internal+0x187/0x2c0\n unbind_store+0xb9/0xe0\n kernfs_fop_write_iter.llvm.11660790530567441834+0xf6/0x180\n vfs_write+0x2a9/0x3b0\n ksys_write+0x5c/0xd0\n do_syscall_64+0x54/0x230\n entry_SYSCALL_64_after_hwframe+0x29/0x31\n [...]\n \u003c/TASK\u003e\n\nThe virtio_balloon device registers 5 queues (inflate, deflate, stats,\nfree_page, reporting) but only the first two are unconditional. The\nstats, free_page and reporting queues are each conditional on their\nrespective feature bits. When any of these features are absent, the\ncorresponding vqs_info entry has name == NULL, creating holes in the\narray.\n\nThe root cause is an indexing mismatch introduced when vq info storage\nwas changed to be passed as an argument. vp_find_vqs_msix() and\nvp_find_vqs_intx() store the info pointer at vp_dev-\u003evqs[i], where \u0027i\u0027\nis the caller\u0027s sparse array index. However, the virtqueue itself gets\nvq-\u003eindex assigned from queue_idx, a dense index that skips NULL\nentries. When holes exist, \u0027i\u0027 and queue_idx diverge. Later,\nvp_del_vqs() looks up info via vp_dev-\u003evqs[vq-\u003eindex] using the dense\nindex into the sparsely-populated array, and hits NULL.\n\nFix this by storing info at vp_dev-\u003evqs[queue_idx] instead of\nvp_dev-\u003evqs[i], so the store index matches the lookup index\n(vq-\u003eindex). Apply the fix to both the MSIX and INTX paths.",
"id": "GHSA-gqwv-4rwr-x42g",
"modified": "2026-07-25T12:31:36Z",
"published": "2026-07-25T12:31:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64457"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/075bc3c779e1ea7294afabdcb7e0a49536959b28"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/41e6dc1a10036c9f47057033f19af7e52ec464b6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/64a4c0befa77bcc01076aec9f93863ffd4ed06b7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f7d380fb525c13bdd114369a1979c80c346e6abc"
}
],
"schema_version": "1.4.0",
"severity": []
}
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