From: Jakub Kicinski <kuba@kernel.org>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Kees Cook <keescook@chromium.org>,
David Ahern <dsahern@kernel.org>,
davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com,
pabeni@redhat.com, linux-hardening@vger.kernel.org
Subject: Re: [PATCH net-next v2] netlink: split up copies in the ack construction
Date: Wed, 16 Nov 2022 17:05:26 -0800 [thread overview]
Message-ID: <20221116170526.752c304b@kernel.org> (raw)
In-Reply-To: <1e97660d-32ff-c0cc-951b-5beda6283571@embeddedor.com>
On Wed, 16 Nov 2022 18:55:36 -0600 Gustavo A. R. Silva wrote:
> > @@ -56,7 +55,6 @@ struct nlmsghdr {
> > __u16 nlmsg_flags;
> > __u32 nlmsg_seq;
> > __u32 nlmsg_pid;
> > - __u8 nlmsg_data[];
> > };
>
> This seems to be a sensible change. In general, it's not a good idea
> to have variable length objects (flex-array members) in structures used
> as headers, and that we know will ultimately be followed by more objects
> when embedded inside other structures.
Meaning we should go back to zero-length arrays instead?
Will this not bring back out-of-bound warnings that Kees
has been fixing?
Is there something in the standard that makes flexible array
at the end of an embedded struct a problem?
Or it's just unlikely compiler people will budge?
AFAICT this is just one of 3 such structs which iproute2 build hits.
next prev parent reply other threads:[~2022-11-17 1:05 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-27 21:25 [PATCH net-next v2] netlink: split up copies in the ack construction Jakub Kicinski
2022-10-31 9:20 ` patchwork-bot+netdevbpf
2022-11-14 2:39 ` David Ahern
2022-11-14 17:06 ` Jakub Kicinski
2022-11-16 22:53 ` Kees Cook
2022-11-16 22:56 ` Kees Cook
2022-11-17 0:27 ` Kees Cook
2022-11-17 0:55 ` Gustavo A. R. Silva
2022-11-17 1:05 ` Jakub Kicinski [this message]
2022-11-17 1:20 ` Gustavo A. R. Silva
2022-11-17 6:13 ` Jakub Kicinski
2022-11-17 16:25 ` Stephen Hemminger
2022-11-17 20:36 ` Jakub Kicinski
2022-11-17 22:35 ` Kees Cook
2022-11-18 0:28 ` Jakub Kicinski
2022-11-18 3:27 ` Kees Cook
2022-11-18 15:59 ` David Ahern
2022-11-18 2:37 ` Stephen Hemminger
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