CVE-2026-93827virtio-fs: avoid double-free on failed queue setup

Official description

In the Linux kernel, the following vulnerability has been resolved: virtio-fs: avoid double-free on failed queue setup virtio_fs_setup_vqs() allocates fs->vqs and fs->mq_map before calling virtio_find_vqs(). If virtio_find_vqs() fails, the error path frees both pointers and returns an error to virtio_fs_probe(). virtio_fs_probe() then drops the last kobject reference, and virtio_fs_ktype_release() frees fs->vqs and fs->mq_map again. This leaves dangling pointers in struct virtio_fs and can trigger a double-free during probe failure cleanup. Set fs->vqs and fs->mq_map to NULL immediately after kfree() in the virtio_fs_setup_vqs() error path so that the later kobject release sees an uninitialized state and kfree(NULL) becomes harmless. This can be reproduced when a broken virtio-fs device advertises more request queues than the transport actually provides. In that case virtio_find_vqs() fails while setting up the extra queue, and the probe path reaches the double-free cleanup sequence.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/3fbc5ee776fefbc6ea34d2518f1f5f90aa2e1dad
• https://git.kernel.org/stable/c/20ef4739b329bb09cff11dd2458795a50674658e
• https://git.kernel.org/stable/c/6af3330ec5d5fb8c06c04eb520a71cf73ea5a765