Re: [PATCH rdma-next 6/8] RDMA/netlink: Protect device query from device removal

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Wed, Dec 27, 2017 at 04:05:52PM -0700, Jason Gunthorpe wrote:
> On Sun, Dec 24, 2017 at 03:43:26PM +0200, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> >
> > There is a chance that device will be removed during device query
> > operations and it will cause to kernel panic in the flows which
> > doesn't hold lists_rwsem semaphore.
> >
> > Fixes: e5c9469efcb1 ("RDMA/netlink: Add nldev device doit implementation")
> > Reviewed-by: Mark Bloch <markb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > Signed-off-by: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> >  drivers/infiniband/core/nldev.c | 25 +++++++++++++++----------
> >  1 file changed, 15 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c
> > index 2b631307349d..e3033d7a4029 100644
> > +++ b/drivers/infiniband/core/nldev.c
> > @@ -141,36 +141,41 @@ static int nldev_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
> >  	struct ib_device *device;
> >  	struct sk_buff *msg;
> >  	u32 index;
> > -	int err;
> > +	int ret = -ENOMEM;
> >
> > -	err = nlmsg_parse(nlh, 0, tb, RDMA_NLDEV_ATTR_MAX - 1,
> > +	ret = nlmsg_parse(nlh, 0, tb, RDMA_NLDEV_ATTR_MAX - 1,
> >  			  nldev_policy, extack);
> > -	if (err || !tb[RDMA_NLDEV_ATTR_DEV_INDEX])
> > +	if (ret || !tb[RDMA_NLDEV_ATTR_DEV_INDEX])
> >  		return -EINVAL;
> >
> >  	index = nla_get_u32(tb[RDMA_NLDEV_ATTR_DEV_INDEX]);
> >
> > -	device = __ib_device_get_by_index(index);
>
> It is not possible to correctly use __ib_device_get_by_index without
> grabbing one of the locks which are static to device.c
>
> Thus it should not be in core_priv.h and every single user must be
> wrong, please fix them all here and make it static again.

Ok, I'll squash patch 6 & 7 and remove the declaration from core_priv.h

Thanks


>
> Jason

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