CVE-2026-64535

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

nvmet-tcp: Fix potential UAF when ddgst mismatch

Shivam Kumar found via vulnerability testing:
When data digest is enabled on an NVMe/TCP connection and a digest
mismatch occurs on a non-final H2C_DATA PDU during an R2T-based
data transfer, the digest error handler in nvmet_tcp_try_recv_ddgst()
calls nvmet_req_uninit() — which performs percpu_ref_put() on the
submission queue — but does NOT mark the command as completed. It
does not set cqe->status, does not modify rbytes_done, and does not
clear any flag. When the subsequent fatal error triggers queue
teardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands,
checks nvmet_tcp_need_data_in() for each one, and finds that the
already-uninited command still appears to need data (because
rbytes_done < transfer_len and cqe->status == 0). It therefore calls
nvmet_req_uninit() a second time on the same command — a double
percpu_ref_put against a single percpu_ref_get.