Hi Leon,

Quoting Leon Romanovsky <l...@kernel.org>:

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 <gust...@embeddedor.com>
---
 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






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