| 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
| ||
|
Date: Wed, 11 Nov 2009 22:05:35 +0200 From: Raimonds Cicans <ray@...llo.lv> To: Ben Hutchings <bhutchings@...arflare.com> CC: romieu@...zoreil.com, netdev@...r.kernel.org Subject: Re: r8169: fix driver drop incoming packets >= 1515 if MTU is set between 1515 and 1536 Ben Hutchings: > On Wed, 2009-11-11 at 20:20 +0200, Raimonds Cicans wrote: >> Driver drop incoming packets >= 1515(1) if MTU is set between 1515(1) and 1536. >> >> 1) exact number depends on some factors: >> - VLAN tagged or not >> - patch "r8169: Fix card drop incoming VLAN tagged MTU byte large jumbo frames" >> applied or not > [...] > > MTU is a limit on transmission; it is not required to limit received > frames. ??? In r8169 driver MTU is used to calculate receive buffer size. Receive buffer size is used to configure hardware incoming packet filter. For jumbo frames: Receive buffer size = Max frame size = MTU + 14 (ethernet header) + 4 (vlan header) + 4 (ethernet checksum) = MTU + 22 Bug: driver for all MTU up to 1536 use receive buffer size 1536 As you can see from formula, this mean all IP packets > 1536 - 22 (for vlan tagged, 1536 - 18 for not tagged) are dropped by hardware filter. Example: host_good> ifconfig eth0 mtu 1536 host_r8169> ifconfig eth0 mtu 1536 host_good> ping host_r8169 Ok host_good> ping -s 1500 host_r8169 Fail host_good> ifconfig eth0 mtu 7000 host_r8169> ifconfig eth0 mtu 7000 host_good> ping -s 1500 host_r8169 Ok Raimonds Cicans -- 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
Powered by blists - more mailing lists