From: Jia Jia <physicalmtea@gmail.com> stable inclusion from stable-v6.6.158 commit 4875c65ca53797a0a402fe2bb54d1b12f28b3cda category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19814 CVE: CVE-2026-97994 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit ccb1dc7c527f8c925925cf92afc76ae590dac311 ] 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. Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend") Signed-off-by: Jia Jia <physicalmtea@gmail.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Message-ID: <20260810010300.132959-1-physicalmtea@gmail.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Conflicts: drivers/vhost/vdpa.c [1. Context conflicts: vdpa_reset() takes the local reset @state argument as the last parameter, so the call in _compat_vdpa_reset() passes both @flags and @state.] Signed-off-by: Jiacheng Yu <yujiacheng3@huawei.com> --- drivers/vhost/vdpa.c | 44 +++++++++++++++++++++++++++++++++++++------- 1 file changed, 37 insertions(+), 7 deletions(-) diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c index c652b26d65fc..99a16fa5ff76 100644 --- a/drivers/vhost/vdpa.c +++ b/drivers/vhost/vdpa.c @@ -62,6 +62,7 @@ struct vhost_vdpa { struct cdev cdev; atomic_t opened; u32 nvqs; + u16 vq_num_max; int virtio_id; int minor; struct eventfd_ctx *config_ctx; @@ -224,7 +225,9 @@ static void vhost_vdpa_unsetup_vq_irq(struct vhost_vdpa *v, u16 qid) static int _compat_vdpa_reset(struct vhost_vdpa *v, int state) { struct vdpa_device *vdpa = v->vdpa; + const struct vdpa_config_ops *ops = vdpa->config; u32 flags = 0; + int ret; if (v->vdev.vqs) { flags |= !vhost_backend_has_feature(v->vdev.vqs[0], @@ -232,7 +235,14 @@ static int _compat_vdpa_reset(struct vhost_vdpa *v, int state) VDPA_RESET_F_CLEAN_MAP : 0; } - return vdpa_reset(vdpa, flags, state); + v->vq_num_max = 0; + ret = vdpa_reset(vdpa, flags, state); + if (!ret) { + /* Some backends derive the max from mutable queue state. */ + v->vq_num_max = ops->get_vq_num_max(vdpa); + } + + return ret; } static int vhost_vdpa_reset(struct vhost_vdpa *v, int state) @@ -844,9 +854,15 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, u32 idx; long r; - r = get_user(idx, (u32 __user *)argp); - if (r < 0) - return r; + if (cmd == VHOST_SET_VRING_NUM) { + if (copy_from_user(&s, argp, sizeof(s))) + return -EFAULT; + idx = s.index; + } else { + r = get_user(idx, (u32 __user *)argp); + if (r < 0) + return r; + } if (idx >= v->nvqs) return -ENOBUFS; @@ -855,6 +871,23 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, vq = &v->vqs[idx]; switch (cmd) { + case VHOST_SET_VRING_NUM: + mutex_lock(&vq->mutex); + if (vq->private_data) { + r = -EBUSY; + } else if (!s.num || s.num > 0xffff || + s.num > v->vq_num_max || + (s.num & (s.num - 1))) { + r = -EINVAL; + } else { + vq->num = s.num; + r = 0; + } + mutex_unlock(&vq->mutex); + if (r) + return r; + ops->set_vq_num(vdpa, idx, s.num); + return 0; case VHOST_VDPA_SET_VRING_ENABLE: if (copy_from_user(&s, argp, sizeof(s))) return -EFAULT; @@ -942,9 +975,6 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, ops->set_vq_cb(vdpa, idx, &cb); break; - case VHOST_SET_VRING_NUM: - ops->set_vq_num(vdpa, idx, vq->num); - break; } return r; -- 2.34.1