CVE-2026-64259

In the Linux kernel, the following vulnerability has been resolved:

fuse-uring: make a fuse_req on SQE commit only findable after memcpy

Bad userspace might try to trick us and send commit SQEs request unique / commit-id of requests that are not even send to fuse-server (iouringcmd_done() not called) yet.

fuseuringcommitfetch() ends the fuse request when the ring entry has a wrong state, but that could have caused a use-after-free with the memcpy operations in fuseuringsendintask(). In order to avoid such races the call of fuseuringaddto_pq() is moved after the copy operations and just before completing the io-uring request - malicious userspace cannot find the request anymore until all prepration work in fuse-client/kernel is completed.

This also moves fuseuringaddtopq() a bit up in the code to avoid a forward declaration. Also not with a preparation commit, to make it easier to back port to older kernels.