netdev - Re: [PATCH net-next] ipv6: add debug checks in fib6_info

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Message-ID: <ee557d3b-79f1-4851-9473-99f711a78f2b@kernel.org>
Date: Tue, 5 Dec 2023 20:41:02 -0700
From: David Ahern <dsahern@...nel.org>
To: Eric Dumazet <edumazet@...gle.com>, "David S . Miller"
 <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net-next] ipv6: add debug checks in fib6_info_release()

On 12/5/23 10:32 AM, Eric Dumazet wrote:
> Some elusive syzbot reports are hinting to fib6_info_release(),
> with a potential dangling f6i->gc_link anchor.
> 
> Add debug checks so that syzbot can catch the issue earlier eventually.
> 
> BUG: KASAN: slab-use-after-free in __hlist_del include/linux/list.h:990 [inline]
> BUG: KASAN: slab-use-after-free in hlist_del_init include/linux/list.h:1016 [inline]
> BUG: KASAN: slab-use-after-free in fib6_clean_expires_locked include/net/ip6_fib.h:533 [inline]
> BUG: KASAN: slab-use-after-free in fib6_purge_rt+0x986/0x9c0 net/ipv6/ip6_fib.c:1064
> Write of size 8 at addr ffff88802805a840 by task syz-executor.1/10057
> 

...

> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---
>  include/net/ip6_fib.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 

Reviewed-by: David Ahern <dsahern@...nel.org>