diff options
| author | Anirudh Rayabharam <mail@anirudhrb.com> | 2022-03-05 15:25:25 +0530 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2022-03-06 06:05:45 -0500 |
| commit | e2ae38cf3d91837a493cb2093c87700ff3cbe667 (patch) | |
| tree | cf757327d49b200da41e138db146ae077b1501c8 /drivers/vhost | |
| parent | b9d102dafec6af1c07b610faf0a6d4e8aee14ae0 (diff) | |
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:
<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: 0bbe30668d89e ("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>
Diffstat (limited to 'drivers/vhost')
| -rw-r--r-- | drivers/vhost/iotlb.c | 11 | ||||
| -rw-r--r-- | drivers/vhost/vhost.c | 5 |
2 files changed, 16 insertions, 0 deletions
diff --git a/drivers/vhost/iotlb.c b/drivers/vhost/iotlb.c index 670d56c879e5..40b098320b2a 100644 --- a/drivers/vhost/iotlb.c +++ b/drivers/vhost/iotlb.c @@ -57,6 +57,17 @@ int vhost_iotlb_add_range_ctx(struct vhost_iotlb *iotlb, if (last < start) return -EFAULT; + /* If the range being mapped is [0, ULONG_MAX], split it into two entries + * otherwise its size would overflow u64. + */ + if (start == 0 && last == ULONG_MAX) { + u64 mid = last / 2; + + vhost_iotlb_add_range_ctx(iotlb, start, mid, addr, perm, opaque); + addr += mid + 1; + start = mid + 1; + } + if (iotlb->limit && iotlb->nmaps == iotlb->limit && iotlb->flags & VHOST_IOTLB_FLAG_RETIRE) { 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 |