From e2ae38cf3d91837a493cb2093c87700ff3cbe667 Mon Sep 17 00:00:00 2001 From: Anirudh Rayabharam Date: Sat, 5 Mar 2022 15:25:25 +0530 Subject: vhost: fix hung thread due to erroneous iotlb entries In vhost_iotlb_add_range_ctx(), range size can overflow to 0 when start is 0 and last is ULONG_MAX. One instance where it can happen is when userspace sends an IOTLB message with iova=size=uaddr=0 (vhost_process_iotlb_msg). So, an entry with size = 0, start = 0, last = ULONG_MAX ends up in the iotlb. Next time a packet is sent, iotlb_access_ok() loops indefinitely due to that erroneous entry. Call Trace: iotlb_access_ok+0x21b/0x3e0 drivers/vhost/vhost.c:1340 vq_meta_prefetch+0xbc/0x280 drivers/vhost/vhost.c:1366 vhost_transport_do_send_pkt+0xe0/0xfd0 drivers/vhost/vsock.c:104 vhost_worker+0x23d/0x3d0 drivers/vhost/vhost.c:372 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Reported by syzbot at: https://syzkaller.appspot.com/bug?extid=0abd373e2e50d704db87 To fix this, do two things: 1. Return -EINVAL in vhost_chr_write_iter() when userspace asks to map a range with size 0. 2. Fix vhost_iotlb_add_range_ctx() to handle the range [0, ULONG_MAX] by splitting it into two entries. Fixes: 0bbe30668d89e ("vhost: factor out IOTLB") Reported-by: syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com Tested-by: syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com Signed-off-by: Anirudh Rayabharam Link: https://lore.kernel.org/r/20220305095525.5145-1-mail@anirudhrb.com Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'drivers/vhost/vhost.c') diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 59edb5a1ffe2..55475fd59fb7 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1170,6 +1170,11 @@ ssize_t vhost_chr_write_iter(struct vhost_dev *dev, goto done; } + if (msg.size == 0) { + ret = -EINVAL; + goto done; + } + if (dev->msg_handler) ret = dev->msg_handler(dev, &msg); else -- cgit v1.2.3 From 4c8093637bc9f8cc2e41eed343c12f85d6ff9e25 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Thu, 13 Jan 2022 15:11:34 +0100 Subject: vhost: remove avail_event arg from vhost_update_avail_event() In vhost_update_avail_event() we never used the `avail_event` argument, since its introduction in commit 2723feaa8ec6 ("vhost: set log when updating used flags or avail event"). Let's remove it to clean up the code. Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20220113141134.186773-1-sgarzare@redhat.com Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/vhost/vhost.c') diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 55475fd59fb7..082380c03a3e 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1986,7 +1986,7 @@ static int vhost_update_used_flags(struct vhost_virtqueue *vq) return 0; } -static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) +static int vhost_update_avail_event(struct vhost_virtqueue *vq) { if (vhost_put_avail_event(vq)) return -EFAULT; @@ -2532,7 +2532,7 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) return false; } } else { - r = vhost_update_avail_event(vq, vq->avail_idx); + r = vhost_update_avail_event(vq); if (r) { vq_err(vq, "Failed to update avail event index at %p: %d\n", vhost_avail_event(vq), r); -- cgit v1.2.3