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  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:   Thu, 14 Mar 2019 05:58:03 -0700
From:   Eric Dumazet <>
To:     Sabrina Dubroca <>,
Cc:     Eric Dumazet <>,
        Jianlin Shi <>,
        Stefano Brivio <>
Subject: Re: [PATCH net] net: enforce xmit_recursion for devices with a queue

On 03/14/2019 03:15 AM, Sabrina Dubroca wrote:
> Commit 745e20f1b626 ("net: add a recursion limit in xmit path")
> introduced a recursion limit, but it only applies to devices without a
> queue. Virtual devices with a queue (either because they don't have
> the IFF_NO_QUEUE flag, or because the administrator added one) can
> still cause an unbounded recursion, via __dev_queue_xmit ->
> __dev_xmit_skb -> qdisc_run -> __qdisc_run -> qdisc_restart ->
> sch_direct_xmit -> dev_hard_start_xmit . Jianlin reported this in a
> setup with 16 gretap devices stacked on top of one another.
> This patch prevents the stack overflow by incrementing xmit_recursion in
> code paths that can call dev_hard_start_xmit() (like commit 745e20f1b626
> did). If the recursion limit is exceeded, the packet is enqueued and the
> qdisc is scheduled.
> Reported-by: Jianlin Shi <>
> Signed-off-by: Sabrina Dubroca <>
> Reviewed-by: Stefano Brivio <>

Hi Sabrina, thanks for the patch.

Can't we detect this in the control path instead ?

Surely this makes no sense in real world to stack 16 devices like that.

Powered by blists - more mailing lists