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From: Jason Wang <jasowang@redhat.com>
To: P J P <ppandit@redhat.com>
Cc: Li Qiang <liqiang6-s@360.cn>, Qemu Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH 1/2] net: pcnet: check rx/tx descriptor ring length
Date: Thu, 20 Oct 2016 10:03:07 +0800	[thread overview]
Message-ID: <0315e8a3-c46e-b1b2-f1ad-b721ecd5f278@redhat.com> (raw)
In-Reply-To: <alpine.LFD.2.20.1609301056160.5531@wniryva>



On 2016年09月30日 13:36, P J P wrote:
>    Hello Jason,
>
> +-- On Fri, 30 Sep 2016, Jason Wang wrote --+
> | On 2016年09月30日 02:57, P J P wrote:
> | > The AMD PC-Net II emulator has set of control and status(CSR)
> | > registers. Of these, CSR76 and CSR78 hold receive and transmit
> | > descriptor ring length respectively. This ring length could range
> | > from 1 to 65535. Setting ring length to zero leads to an infinite
> | > loop in pcnet_rdra_addr. Add check to avoid it.
> |
> | In this case, we only need to protect RCVRL I believe? (since XMTRL were not
> | used).
>
>    XMTRL is not used in this case, but could be prone to similar issues. For
> ex.
>
>      static void pcnet_transmit(PCNetState *s)
>      {
>          int count = CSR_XMTRL(s) - 1;
>          ...
>          if (count--)
>              goto txagain;
>      }
>
> If CSR_XMTRL is set to zero(0), 'count' would never reach zero and function
> would continue to jump to 'txagain'.

Applied and tweak the commit log by mentioning pcnet_transmit() too.

Thanks

>
> Thank you.
> --
> Prasad J Pandit / Red Hat Product Security Team
> 47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F

  reply	other threads:[~2016-10-20  2:03 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-29 18:57 [Qemu-devel] [PATCH 0/2] net: pcnet: fix infinite loop and source format P J P
2016-09-29 18:57 ` [Qemu-devel] [PATCH 1/2] net: pcnet: check rx/tx descriptor ring length P J P
2016-09-30  3:06   ` Jason Wang
2016-09-30  5:36     ` P J P
2016-10-20  2:03       ` Jason Wang [this message]
2016-09-29 18:57 ` [Qemu-devel] [PATCH 2/2] net: pcnet: fix source formatting and indentation P J P
2016-09-30  3:08   ` Jason Wang
2016-09-30  6:50     ` P J P
2016-09-29 19:08 ` [Qemu-devel] [PATCH 0/2] net: pcnet: fix infinite loop and source format no-reply

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