netdev - Re: [PATCH] net: usb: ax88179_178a: fix packet alignment padding

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]

Date:   Wed, 17 Jun 2020 08:56:39 +0800
From:   Jeremy Kerr <jk@...abs.org>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, allan@...x.com.tw, freddy@...x.com.tw,
        pfink@...ist-es.de, linux-usb@...r.kernel.org, louis@...x.com.tw
Subject: Re: [PATCH] net: usb: ax88179_178a: fix packet alignment padding

Hi David,

> It seems logical to me that what the chip does is align up the total
> sub-packet length to a multiple of 4 or larger, and then add those two
> prefix padding bytes.  Otherwise the prefix padding won't necessarily
> and reliably align the IP header after the link level header.

Yep, that makes sense, and is what the driver is currently doing;
between clustered packets, the header is aligned (up) to 8 bytes, then
the 2-byte padding is added to that.

For this change, I have assumed that the packet length behaviour (ie,
describing the un-padded length) is consistent between clustered
packets.

[If you have any hints for forcing clustered packets, I'll see if I can
probe the behaviour a little better to confirm]

Cheers,


Jeremy