From 0d78289c3dca3de8e614a551a3d4a9415168ace0 Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Fri, 13 Jan 2017 18:18:20 +0100 Subject: 9pfs: fix off-by-one error in PDU free list The server can handle MAX_REQ - 1 PDUs at a time and the virtio-9p device has a MAX_REQ sized virtqueue. If the client manages to fill up the virtqueue, pdu_alloc() will fail and the request won't be processed without any notice to the client (it actually causes the linux 9p client to hang). This has been there since the beginning (commit 9f10751365b2 "virtio-9p: Add a virtio 9p device to qemu"), but it needs an agressive workload to run in the guest to show up. We actually allocate MAX_REQ PDUs and I see no reason not to link them all into the free list, so let's fix the init loop. Reported-by: Tuomas Tynkkynen Suggested-by: Al Viro Signed-off-by: Greg Kurz --- hw/9pfs/9p.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'hw/9pfs') diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 58310ca..d2d0288 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -3454,7 +3454,7 @@ int v9fs_device_realize_common(V9fsState *s, Error **errp) /* initialize pdu allocator */ QLIST_INIT(&s->free_list); QLIST_INIT(&s->active_list); - for (i = 0; i < (MAX_REQ - 1); i++) { + for (i = 0; i < MAX_REQ; i++) { QLIST_INSERT_HEAD(&s->free_list, &s->pdus[i], next); s->pdus[i].s = s; s->pdus[i].idx = i; -- cgit v1.1