CVE-2026-64509rust: block: fix GenDisk cleanup paths

Official description

In the Linux kernel, the following vulnerability has been resolved: rust: block: fix GenDisk cleanup paths GenDiskBuilder::build() still has fallible work after __blk_mq_alloc_disk(), but its error path only recovers the foreign queue data. That leaks the temporary gendisk and request_queue until later teardown. If the caller moved the last Arc<TagSet<T>> into build(), the leaked queue can retain blk-mq state after the tag set is dropped. Fix the pre-registration failure path by dropping the temporary gendisk reference with put_disk() before recovering queue_data, so disk_release() can tear down the owned queue. Also pair GenDisk::drop() with put_disk() after del_gendisk(). Once a Rust GenDisk has been added with device_add_disk(), del_gendisk() only unregisters it; the final gendisk reference still has to be dropped to complete the release path.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/d1dcaa5229a63a6b6df7e0f673fe576cf3d6e8cb
• https://git.kernel.org/stable/c/e7636f26f77070a529c26d65afd217514ce85ce4
• https://git.kernel.org/stable/c/6822a2685b4da9a87efd1fce4b042678a31ff734
• https://git.kernel.org/stable/c/2957771379fa335103a4b539db57bb2271e12142