virtio_pci: fix vq info pointer lookup via wrong index

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Summary

CVECVE-2026-64457
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-25 10:17:30 UTC
Updated2026-07-25 10:17:30 UTC
DescriptionIn 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.

Risk And Classification

EPSS: 0.002090000 probability, percentile 0.111720000 (date 2026-07-25)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 89a1c435aec269d109ed46ca7bbb10fa8edf7ace 41e6dc1a10036c9f47057033f19af7e52ec464b6 git Not specified
CNA Linux Linux affected 89a1c435aec269d109ed46ca7bbb10fa8edf7ace 075bc3c779e1ea7294afabdcb7e0a49536959b28 git Not specified
CNA Linux Linux affected 89a1c435aec269d109ed46ca7bbb10fa8edf7ace 64a4c0befa77bcc01076aec9f93863ffd4ed06b7 git Not specified
CNA Linux Linux affected 89a1c435aec269d109ed46ca7bbb10fa8edf7ace f7d380fb525c13bdd114369a1979c80c346e6abc git Not specified
CNA Linux Linux affected 6.11 Not specified
CNA Linux Linux unaffected 6.11 semver Not specified
CNA Linux Linux unaffected 6.12.96 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.39 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.4 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/64a4c0befa77bcc01076aec9f93863ffd4ed06b7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/075bc3c779e1ea7294afabdcb7e0a49536959b28 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f7d380fb525c13bdd114369a1979c80c346e6abc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/41e6dc1a10036c9f47057033f19af7e52ec464b6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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