netdev - Re: [PATCHv4 net-next 2/3] sunvnet: allow admin to set sunvnet MTU

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <541886B9.3010206@oracle.com>
Date:	Tue, 16 Sep 2014 14:51:37 -0400
From:	David L Stevens <david.stevens@...cle.com>
To:	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org
Subject: Re: [PATCHv4 net-next 2/3] sunvnet: allow admin to set sunvnet MTU



On 09/15/2014 08:35 PM, David L Stevens wrote:

>   */
>  #define VNET_TX_TIMEOUT			(5 * HZ)
>  
> -#define VNET_MAXPACKET			1518ULL /* ETH_FRAMELEN + VLAN_HDR */
> +#define VNET_MAXPACKET			65553ULL /* 64K-1  +ETH HDR +VLAN HDR*/
>  #define VNET_TX_RING_SIZE		512
>  #define VNET_TX_WAKEUP_THRESH(dr)	((dr)->pending / 4)

While looking at adding TSO support, I've turned up a bug with this.

The transmit buffer mapping should be using a cookie per-page and this increases
the page count (without page alignment) from 2 with a 1500-byte MTU to 10 with a 64K MTU
+ framing and allowing from unaligned buffers.

I think it worked during my testing because the pages were contiguous, but the tx buffer
allocation code is assuming 2 pages (and 2 cookies) max.

So, it's incorrect. I'll fix and repost; please don't apply these yet.

							+-DLS

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html