From: Stephen Hemminger <stephen@networkplumber•org>
To: Cong Wang <xiyou.wangcong@gmail•com>
Cc: netdev@vger•kernel.org
Subject: Re: [Bug 60669] Kernel panic when using negative priority for HTB class
Date: Thu, 1 Aug 2013 22:31:15 -0700 [thread overview]
Message-ID: <20130801223115.59a1ac76@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <ktfdq8$882$1@ger.gmane.org>
On Fri, 2 Aug 2013 04:50:16 +0000 (UTC)
Cong Wang <xiyou.wangcong@gmail•com> wrote:
> On Fri, 02 Aug 2013 at 04:12 GMT, Stephen Hemminger <stephen@networkplumber•org> wrote:
> >
> > --- Comment #2 from _Vi <vi0oss@gmail•com> ---
> > Reproducible on 3.11.0-rc3
> >
> > Looks like negative priority value is essential for the kernel panic.
> >
>
> There is a check for prio:
>
> if ((cl->prio = hopt->prio) >= TC_HTB_NUMPRIO)
> cl->prio = TC_HTB_NUMPRIO - 1;
>
This maybe related to or old bugs, 64 bit with current
iproute2 the error is caught at the command level.
The issue is that hopt->prio is u32 but cl->prio is int.
Example:
int main()
{
int x = -1;
uint32_t prio = x;
int cl;
if ((cl = prio) >= TC_HTB_NUMPRIO)
cl = TC_HTB_NUMPRIO - 1;
printf("%d %u %d\n", x, prio, cl);
return 0;
}
-1 4294967295 -1
Signed/unsigned conversions can bite.
next prev parent reply other threads:[~2013-08-02 5:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-02 4:12 Fw: [Bug 60669] Kernel panic when using negative priority for HTB class Stephen Hemminger
2013-08-02 4:50 ` Cong Wang
2013-08-02 5:31 ` Stephen Hemminger [this message]
[not found] ` <20130801221936.24d4b31e@nehalam.linuxnetplumber.net>
2013-08-02 5:32 ` [PATCH net-next] htb: fix sign extension bug Stephen Hemminger
2013-08-02 13:36 ` Eric Dumazet
2013-08-02 15:24 ` Stephen Hemminger
2013-08-02 21:53 ` David Miller
2013-08-02 21:52 ` David Miller
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