netdev - Re: [PATCH net-next] ipv6: do not check fib6_has_expires() in fib6_info

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Date: Thu, 7 Dec 2023 13:25:58 -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,
 syzbot+c15aa445274af8674f41@...kaller.appspotmail.com,
 Kui-Feng Lee <thinker.li@...il.com>
Subject: Re: [PATCH net-next] ipv6: do not check fib6_has_expires() in
 fib6_info_release()

On 12/7/23 1:13 PM, Eric Dumazet wrote:
> My prior patch went a bit too far, because apparently fib6_has_expires()
> could be true while f6i->gc_link is not hashed yet.

yes, and I got distracted by that stack trace and avoiding errors in the
create function. The diff I sent does not solve any corruption with list
since the newly allocated f6i is not linked (and gc-link is initialized).

Kui-Feng: no need to send that patch again since it is not really
changing anything. Let's see if the other warn on triggers.

> 
> fib6_set_expires_locked() can indeed set RTF_EXPIRES
> while f6i->fib6_table is NULL.
> 
> Original syzbot reports were about corruptions caused
> by dangling f6i->gc_link.
> 
> Fixes: 5a08d0065a91 ("ipv6: add debug checks in fib6_info_release()")
> Reported-by: syzbot+c15aa445274af8674f41@...kaller.appspotmail.com
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: David Ahern <dsahern@...nel.org>
> Cc: Kui-Feng Lee <thinker.li@...il.com>
> ---
>  include/net/ip6_fib.h | 1 -
>  1 file changed, 1 deletion(-)
> 

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