From: Anirudh Rayabharam <mail@anirudhrb.com>
To: "Michael S. Tsirkin" <mst@redhat.com>, Jason Wang <jasowang@redhat.com>
Cc: mail@anirudhrb.com,
syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com,
kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] vhost: validate range size before adding to iotlb
Date: Tue, 22 Feb 2022 01:23:03 +0530 [thread overview]
Message-ID: <20220221195303.13560-1-mail@anirudhrb.com> (raw)
In vhost_iotlb_add_range_ctx(), validate the range size is non-zero
before proceeding with adding it to the iotlb.
Range size can overflow to 0 when start is 0 and last is (2^64 - 1).
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 = (2^64 - 1) 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
Reported-by: syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com
Tested-by: syzbot+0abd373e2e50d704db87@syzkaller.appspotmail.com
Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
---
drivers/vhost/iotlb.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/iotlb.c b/drivers/vhost/iotlb.c
index 670d56c879e5..b9de74bd2f9c 100644
--- a/drivers/vhost/iotlb.c
+++ b/drivers/vhost/iotlb.c
@@ -53,8 +53,10 @@ int vhost_iotlb_add_range_ctx(struct vhost_iotlb *iotlb,
void *opaque)
{
struct vhost_iotlb_map *map;
+ u64 size = last - start + 1;
- if (last < start)
+ // size can overflow to 0 when start is 0 and last is (2^64 - 1).
+ if (last < start || size == 0)
return -EFAULT;
if (iotlb->limit &&
@@ -69,7 +71,7 @@ int vhost_iotlb_add_range_ctx(struct vhost_iotlb *iotlb,
return -ENOMEM;
map->start = start;
- map->size = last - start + 1;
+ map->size = size;
map->last = last;
map->addr = addr;
map->perm = perm;
--
2.35.1
next reply other threads:[~2022-02-21 19:53 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-21 19:53 Anirudh Rayabharam [this message]
2022-02-22 2:50 ` [PATCH] vhost: validate range size before adding to iotlb Jason Wang
2022-02-22 2:50 ` Jason Wang
2022-02-22 4:57 ` Anirudh Rayabharam
2022-02-22 7:11 ` Jason Wang
2022-02-22 7:11 ` Jason Wang
2022-02-22 15:02 ` Michael S. Tsirkin
2022-02-22 15:02 ` Michael S. Tsirkin
2022-02-22 17:27 ` Anirudh Rayabharam
2022-02-22 23:21 ` Michael S. Tsirkin
2022-02-22 23:21 ` Michael S. Tsirkin
2022-02-23 14:18 ` Anirudh Rayabharam
2022-02-23 15:15 ` Michael S. Tsirkin
2022-02-23 15:15 ` Michael S. Tsirkin
2022-02-23 16:49 ` Anirudh Rayabharam
2022-02-23 17:14 ` Michael S. Tsirkin
2022-02-23 17:14 ` Michael S. Tsirkin
2022-02-23 2:05 ` Jason Wang
2022-02-23 2:05 ` Jason Wang
2022-02-22 14:04 ` Michael S. Tsirkin
2022-02-22 14:04 ` Michael S. Tsirkin
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