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CVE-2026-97994

vhost/vdpa: reject VRING_NUM larger than device max PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: vhost/vdpa: reject VRING_NUM larger than device max vhost_vring_set_num() accepts any non-zero power-of-two queue size that fits in 16 bits. vhost-vdpa then passes that value to set_vq_num() without comparing it with get_vq_num_max(). A process with access to /dev/vhost-vdpa-* can therefore configure a queue larger than the device advertises. With vdpa_sim, the worker can walk descriptors beyond the mapped descriptor ring. KASAN reports a 16-byte out-of-bounds read, corresponding to one vring_desc, in the vringh IOTLB path: BUG: KASAN: out-of-bounds in _copy_from_iter Read of size 16 copy_from_iotlb copydesc_iotlb vringh_getdesc_iotlb vdpasim_net_work Cache get_vq_num_max() immediately after reset. Some backends derive it from writable queue-size state, so querying it after SET_NUM may return the current size instead of the device capability. Invalidate the cached value before reset so a failed reset leaves SET_NUM disabled. For VHOST_SET_VRING_NUM, copy the complete vring state once and use the same index and size for validation, vq->num, and set_vq_num(). This ensures that validation and use operate on the same copied values.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 4c8cf31885f69e86be0b5b9e6677a26797365e1d before 4875c65ca53797a0a402fe2bb54d1b12f28b3cda; affected 4c8cf31885f69e86be0b5b9e6677a26797365e1d before 1d09201d81b7d3e276860cc7b7dbf6c6cbe8e9b4; affected 4c8cf31885f69e86be0b5b9e6677a26797365e1d before 68232102f20fc961327fb9e0f605a7eaadf030a9; affected 4c8cf31885f69e86be0b5b9e6677a26797365e1d before 59522639a7d71cff4e20d594d0b9ea30dd0c77e0; affected 4c8cf31885f69e86be0b5b9e6677a26797365e1d before ccb1dc7c527f8c925925cf92afc76ae590dac311
Linux / Linuxaffected 5.7; unaffected 0 before 5.7; unaffected 6.6.158 through 6.6.*; unaffected 6.12.111 through 6.12.*; unaffected 6.18.53 through 6.18.*; unaffected 7.2.7 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References