[PATCH v2 19/51] hw/nvme: fix aio cancel in zone reset

[Juan Quintela]

From: Klaus Jensen <k.jensen@samsung.com>

If the zone reset operation is cancelled but the block unmap operation
completes normally, the callback will continue resetting the next zone
since it neglects to check iocb->ret which will have been set to
-ECANCELED. Make sure that this is checked and bail out if an error is
present.

Secondly, fix a potential use-after-free by removing the bottom half and
enqueuing the completion directly.

Fixes: 63d96e4ffd71 ("hw/nvme: reimplement zone reset to allow cancellation")
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
 hw/nvme/ctrl.c | 36 +++++++++++-------------------------
 1 file changed, 11 insertions(+), 25 deletions(-)

diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index fede5af6af..bf4abf73f7 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -3712,7 +3712,6 @@ typedef struct NvmeZoneResetAIOCB {
     BlockAIOCB common;
     BlockAIOCB *aiocb;
     NvmeRequest *req;
-    QEMUBH *bh;
     int ret;
 
     bool all;
@@ -3741,17 +3740,6 @@ static const AIOCBInfo nvme_zone_reset_aiocb_info = {
     .cancel_async = nvme_zone_reset_cancel,
 };
 
-static void nvme_zone_reset_bh(void *opaque)
-{
-    NvmeZoneResetAIOCB *iocb = opaque;
-
-    iocb->common.cb(iocb->common.opaque, iocb->ret);
-
-    qemu_bh_delete(iocb->bh);
-    iocb->bh = NULL;
-    qemu_aio_unref(iocb);
-}
-
 static void nvme_zone_reset_cb(void *opaque, int ret);
 
 static void nvme_zone_reset_epilogue_cb(void *opaque, int ret)
@@ -3762,14 +3750,8 @@ static void nvme_zone_reset_epilogue_cb(void *opaque, 
int ret)
     int64_t moff;
     int count;
 
-    if (ret < 0) {
-        nvme_zone_reset_cb(iocb, ret);
-        return;
-    }
-
-    if (!ns->lbaf.ms) {
-        nvme_zone_reset_cb(iocb, 0);
-        return;
+    if (ret < 0 || iocb->ret < 0 || !ns->lbaf.ms) {
+        goto out;
     }
 
     moff = nvme_moff(ns, iocb->zone->d.zslba);
@@ -3779,6 +3761,9 @@ static void nvme_zone_reset_epilogue_cb(void *opaque, int 
ret)
                                         BDRV_REQ_MAY_UNMAP,
                                         nvme_zone_reset_cb, iocb);
     return;
+
+out:
+    nvme_zone_reset_cb(iocb, ret);
 }
 
 static void nvme_zone_reset_cb(void *opaque, int ret)
@@ -3787,7 +3772,9 @@ static void nvme_zone_reset_cb(void *opaque, int ret)
     NvmeRequest *req = iocb->req;
     NvmeNamespace *ns = req->ns;
 
-    if (ret < 0) {
+    if (iocb->ret < 0) {
+        goto done;
+    } else if (ret < 0) {
         iocb->ret = ret;
         goto done;
     }
@@ -3835,9 +3822,9 @@ static void nvme_zone_reset_cb(void *opaque, int ret)
 
 done:
     iocb->aiocb = NULL;
-    if (iocb->bh) {
-        qemu_bh_schedule(iocb->bh);
-    }
+
+    iocb->common.cb(iocb->common.opaque, iocb->ret);
+    qemu_aio_unref(iocb);
 }
 
 static uint16_t nvme_zone_mgmt_send_zrwa_flush(NvmeCtrl *n, NvmeZone *zone,
@@ -3942,7 +3929,6 @@ static uint16_t nvme_zone_mgmt_send(NvmeCtrl *n, 
NvmeRequest *req)
                            nvme_misc_cb, req);
 
         iocb->req = req;
-        iocb->bh = qemu_bh_new(nvme_zone_reset_bh, iocb);
         iocb->ret = 0;
         iocb->all = all;
         iocb->idx = zone_idx;
-- 
2.38.1