From: Minwoo Im <[email protected]> nvme_ctrl_reset() freed every SQ/CQ right after nvme_ns_drain(), which only waits out requests on a per-namespace BlockBackend. That is safe as long as the guest first tore down I/O queues gracefully (Delete I/O SQ/CQ), since nvme_del_sq() already cancels and waits for anything left on a queue before freeing it.
A reset that happens without that graceful sequence first (e.g. an abrupt/asynchronous controller reset) can still have commands inflight on blk_aio_*. Freeing sq/cq before those complete leaves their completion callbacks (nvme_rw_cb() and friends) to run against already-freed NvmeRequest/NvmeSQueue/NvmeCQueue memory via nvme_enqueue_req_completion(), causing a use-after-free/segfault. Run nvme_sq_cancel_inflight() over every queue in nvme_ctrl_reset() before the free loops, so no in-flight blk_aio_* callback can fire after sq/cq memory is freed. Cc: [email protected] Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3398 Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3883 Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4068 Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4072 Signed-off-by: Minwoo Im <[email protected]> Signed-off-by: Klaus Jensen <[email protected]> (cherry picked from commit 86f938333e2faae7c60ca66c0809f5495c59aa4b) (Mjt: back-port across v11.0.0-2641-g9d378cab537d "hw/nvme: add basic live migration support" which changed by-queue loops upper bound from `n->params.max_ioqpairs + 1' to `n->num_queues') Signed-off-by: Michael Tokarev <[email protected]> diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c index 64241cca8f7..325b06970c6 100644 --- a/hw/nvme/ctrl.c +++ b/hw/nvme/ctrl.c @@ -7657,6 +7657,18 @@ static void nvme_ctrl_reset(NvmeCtrl *n, NvmeResetType rst) nvme_ns_drain(ns); } + /* + * Cancel and wait out every inflight command on every queue first. A + * reset is not required to be preceded by the guest's graceful + * Delete I/O SQ/CQ sequence, so sq/cq must not be freed below while a + * blk_aio_* completion for them could still be in flight. + */ + for (i = 0; i < n->params.max_ioqpairs + 1; i++) { + if (n->sq[i] != NULL) { + nvme_sq_cancel_inflight(n->sq[i], NVME_CMD_ABORT_SQ_DEL); + } + } + for (i = 0; i < n->params.max_ioqpairs + 1; i++) { if (n->sq[i] != NULL) { nvme_free_sq(n->sq[i], n); -- 2.47.3
