From: Simon Horman <simon.horman@corigine.com>
To: Kees Cook <keescook@chromium.org>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
Jiri Pirko <jiri@resnulli.us>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] net: sched: sch: Bounds check priority
Date: Sat, 28 Jan 2023 14:43:28 +0100 [thread overview]
Message-ID: <Y9UmgDQibo7Z0Nqz@corigine.com> (raw)
In-Reply-To: <20230127224036.never.561-kees@kernel.org>
On Fri, Jan 27, 2023 at 02:40:37PM -0800, Kees Cook wrote:
> Nothing was explicitly bounds checking the priority index used to access
> clpriop[]. WARN and bail out early if it's pathological. Seen with GCC 13:
>
> ../net/sched/sch_htb.c: In function 'htb_activate_prios':
> ../net/sched/sch_htb.c:437:44: warning: array subscript [0, 31] is outside array bounds of 'struct htb_prio[8]' [-Warray-bounds=]
> 437 | if (p->inner.clprio[prio].feed.rb_node)
> | ~~~~~~~~~~~~~~~^~~~~~
> ../net/sched/sch_htb.c:131:41: note: while referencing 'clprio'
> 131 | struct htb_prio clprio[TC_HTB_NUMPRIO];
> | ^~~~~~
>
...
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> net/sched/sch_htb.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
I'm not sure what will happen if we hit the 'break' case.
But I also think that warning and bailing out is an improvement on whatever
happens now if that scenario is hit.
Reviewed-by: Simon Horman <simon.horman@corigine.com>
> diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
> index f46643850df8..cc28e41fb745 100644
> --- a/net/sched/sch_htb.c
> +++ b/net/sched/sch_htb.c
> @@ -431,7 +431,10 @@ static void htb_activate_prios(struct htb_sched *q, struct htb_class *cl)
> while (cl->cmode == HTB_MAY_BORROW && p && mask) {
> m = mask;
> while (m) {
> - int prio = ffz(~m);
> + unsigned int prio = ffz(~m);
> +
> + if (WARN_ON_ONCE(prio > ARRAY_SIZE(p->inner.clprio)))
> + break;
> m &= ~(1 << prio);
>
> if (p->inner.clprio[prio].feed.rb_node)
> --
> 2.34.1
>
next prev parent reply other threads:[~2023-01-28 13:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-27 22:40 [PATCH] net: sched: sch: Bounds check priority Kees Cook
2023-01-28 13:43 ` Simon Horman [this message]
2023-01-28 19:29 ` Cong Wang
2023-01-31 10:10 ` patchwork-bot+netdevbpf
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