netdev - Re: [PATCH net] ipv6: fix possible deadlock in rt6_age_examine

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-Id: <20180323.134158.493019552934178147.davem@davemloft.net>
Date:   Fri, 23 Mar 2018 13:41:58 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com, weiwan@...gle.com,
        kafai@...com
Subject: Re: [PATCH net] ipv6: fix possible deadlock in
 rt6_age_examine_exception()

From: Eric Dumazet <edumazet@...gle.com>
Date: Fri, 23 Mar 2018 07:56:58 -0700

> syzbot reported a LOCKDEP splat [1] in rt6_age_examine_exception()
> 
> rt6_age_examine_exception() is called while rt6_exception_lock is held.
> This lock is the lower one in the lock hierarchy, thus we can not
> call dst_neigh_lookup() function, as it can fallback to neigh_create()
> 
> We should instead do a pure RCU lookup. As a bonus we avoid
> a pair of atomic operations on neigh refcount.
> 
> [1]
 ...
> Fixes: c757faa8bfa2 ("ipv6: prepare fib6_age() for exception table")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Applied and queued up for -stable, thanks Eric.