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:
<TASK>
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
</TASK>
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: 0bbe30668d ("vhost: factor out IOTLB")
Reported-by: syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com
Tested-by: syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com
Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
Link: https://lore.kernel.org/r/20220305095525.5145-1-mail@anirudhrb.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Trivial change for the vhost_iotlb_del_range() documentation,
fixing the function name in the comment block.
Discovered with `make C=2 M=drivers/vhost`:
../drivers/vhost/iotlb.c:92: warning: expecting prototype for vring_iotlb_del_range(). Prototype was for vhost_iotlb_del_range() instead
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210504135444.158716-1-sgarzare@redhat.com
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch factors out IOTLB into a dedicated module in order to be
reused by other modules like vringh. User may choose to enable the
automatic retiring by specifying VHOST_IOTLB_FLAG_RETIRE flag to fit
for the case of vhost device IOTLB implementation.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20200326140125.19794-4-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
