On 2018年09月28日 07:50, Michael S. Tsirkin wrote:
On Fri, Sep 28, 2018 at 07:37:37AM +0800, Jason Wang wrote:
On 2018年09月28日 01:04, Michael S. Tsirkin wrote:
On Thu, Sep 27, 2018 at 08:22:04PM +0800, Jason Wang wrote:
The access of vsock is not protected by vhost_vsock_lock. This may
lead to use after free since vhost_vsock_dev_release() may free the
pointer at the same time.
Fix this by holding the lock during the access.
Reported-by:syzbot+e3e074963495f92a89ed@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 16320f363ae1 ("vhost-vsock: add pkt cancel capability")
Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko")
Cc: Stefan Hajnoczi<stefanha@xxxxxxxxxx>
Signed-off-by: Jason Wang<jasowang@xxxxxxxxxx>
Wow is that really the best we can do?
For net/stable, probably yes.
A global lock on a data path
operation?
It's already there,
&vhost_vsock_lock? were is it takes on data path?
Ok, but the current code use list which means a global lock is needed
anyway here.
and the patch only increase the critical section.
Granted use after free is nasty but Stefan said he sees
a way to fix it using a per socket refcount. He's on vacation
until Oct 4 though ...
Stefan has acked the pacth, so I think it's ok? We can do optimization for
-next on top.
Thanks
Well on high SMP serializing can drop performance as much as x100 so I'm
not sure it's appropriate - seems to fix a bug but can introduce a
regression. Let's see how does a proper fix look first?
It looks to me hlist + RCU is better. But I'm not sure it's suitable for
-net/-stable.
Thanks
