[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Wed, 09 Sep 2020 11:33:11 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: Jason@...c4.com
Cc: netdev@...r.kernel.org, edumazet@...gle.com
Subject: Re: [PATCH net 0/2] wireguard fixes for 5.9-rc5
From: "Jason A. Donenfeld" <Jason@...c4.com>
Date: Wed, 9 Sep 2020 13:58:13 +0200
> Yesterday, Eric reported a race condition found by syzbot. This series
> contains two commits, one that fixes the direct issue, and another that
> addresses the more general issue, as a defense in depth.
>
> 1) The basic problem syzbot unearthed was that one particular mutation
> of handshake->entry was not protected by the handshake mutex like the
> other cases, so this patch basically just reorders a line to make
> sure the mutex is actually taken at the right point. Most of the work
> here went into making sure the race was fully understood and making a
> reproducer (which syzbot was unable to do itself, due to the rarity
> of the race).
>
> 2) Eric's initial suggestion for fixing this was taking a spinlock
> around the hash table replace function where the null ptr deref was
> happening. This doesn't address the main problem in the most precise
> possible way like (1) does, but it is a good suggestion for
> defense-in-depth, in case related issues come up in the future, and
> basically costs nothing from a performance perspective. I thought it
> aided in implementing a good general rule: all mutators of that hash
> table take the table lock. So that's part of this series as a
> companion.
>
> Both of these contain Fixes: tags and are good candidates for stable.
Series applied and queued up for -stable, thanks.
Powered by blists - more mailing lists