Re: [PATCH] RDMA/nldev: Fix multiple potential NULL pointer dereferences

[Gustavo A. R. Silva]

Hi Leon,

Quoting Leon Romanovsky <leon@xxxxxxxxxx>:

> On Fri, Feb 09, 2018 at 12:37:02AM -0600, Gustavo A. R. Silva wrote:
> > In case the message header and payload cannot be stored, function
> > nlmsg_put returns null.
> >
> > Fix this by adding multiple sanity checks and avoid a potential
> > null dereference on _nlh_ when calling nlmsg_end.
> >
> > Addresses-Coverity-ID: 1454215 ("Dereference null return value")
> > Addresses-Coverity-ID: 1454223 ("Dereference null return value")
> > Addresses-Coverity-ID: 1454224 ("Dereference null return value")
> > Addresses-Coverity-ID: 1464669 ("Dereference null return value")
> > Addresses-Coverity-ID: 1464670 ("Dereference null return value")
> > Addresses-Coverity-ID: 1464672 ("Dereference null return value")
> > Fixes: e5c9469efcb1 ("RDMA/netlink: Add nldev device doit implementation")
> > Fixes: c3f66f7b0052 ("RDMA/netlink: Implement nldev port doit callback")
> > Fixes: 7d02f605f0dc ("RDMA/netlink: Add nldev port dumpit implementation")
> > Fixes: b5fa635aab8f ("RDMA/nldev: Provide detailed QP information")
> > Fixes: bf3c5a93c523 ("RDMA/nldev: Provide global resource utilization")
> > Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> > ---
> >  drivers/infiniband/core/nldev.c | 26 +++++++++++++++++++++++++-
> >  1 file changed, 25 insertions(+), 1 deletion(-)
>
> It will be much better to fix the tool instead of fixing ghost case.
> This scenario is impossible for all those flows.
> We can receive the skv/msg in two ways:
>  * First by allocating new message with NLMSG_DEFAULT_SIZE, which  
> has more room
>    than nlmsg_total_size(payload), payload is 0.
>  * Second by getting from netlink.c and it will be at least "struct  
> nlmsghdr" too.
>
> Can you please add this info to the commit message?

Actually, I was planing to send a new version of this patch. This time  
using the unlikely macro for all the null checks on nlh.

What do you think?

Thanks
--
Gustavo