From: Jakub Kicinski <kuba@kernel.org>
To: Sven Eckelmann <sven@narfation.org>, mareklindner@neomailbox.ch
Cc: sw@simonwunderlich.de, a@unstable.cc, davem@davemloft.net,
Pavel Skripkin <paskripkin@gmail.com>,
b.a.t.m.a.n@lists.open-mesh.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
syzbot+28b0702ada0bf7381f58@syzkaller.appspotmail.com
Subject: Re: [PATCH] net: batman-adv: fix error handling
Date: Mon, 25 Oct 2021 17:49:50 -0700 [thread overview]
Message-ID: <20211025174950.1bec22fb@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <2526100.mKikVBQdmv@sven-l14>
On Sun, 24 Oct 2021 16:58:30 +0200 Sven Eckelmann wrote:
> On Sunday, 24 October 2021 15:13:56 CEST Pavel Skripkin wrote:
> > Syzbot reported ODEBUG warning in batadv_nc_mesh_free(). The problem was
> > in wrong error handling in batadv_mesh_init().
> >
> > Before this patch batadv_mesh_init() was calling batadv_mesh_free() in case
> > of any batadv_*_init() calls failure. This approach may work well, when
> > there is some kind of indicator, which can tell which parts of batadv are
> > initialized; but there isn't any.
> >
> > All written above lead to cleaning up uninitialized fields. Even if we hide
> > ODEBUG warning by initializing bat_priv->nc.work, syzbot was able to hit
> > GPF in batadv_nc_purge_paths(), because hash pointer in still NULL. [1]
> >
> > To fix these bugs we can unwind batadv_*_init() calls one by one.
> > It is good approach for 2 reasons: 1) It fixes bugs on error handling
> > path 2) It improves the performance, since we won't call unneeded
> > batadv_*_free() functions.
> >
> > So, this patch makes all batadv_*_init() clean up all allocated memory
> > before returning with an error to no call correspoing batadv_*_free()
> > and open-codes batadv_mesh_free() with proper order to avoid touching
> > uninitialized fields.
> >
> > Link: https://lore.kernel.org/netdev/000000000000c87fbd05cef6bcb0@google.com/ [1]
> > Reported-and-tested-by: syzbot+28b0702ada0bf7381f58@syzkaller.appspotmail.com
> > Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
> > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
>
> Acked-by: Sven Eckelmann <sven@narfation.org>
FWIW I'm marking this as "Awaiting upstream" in netdev patchwork,
please LMK if you prefer for it to be applied directly.
next prev parent reply other threads:[~2021-10-26 0:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-21 23:19 [syzbot] WARNING in batadv_nc_mesh_free syzbot
2021-10-22 18:33 ` Pavel Skripkin
2021-10-22 20:20 ` syzbot
2021-10-22 20:57 ` Pavel Skripkin
2021-10-22 20:58 ` Pavel Skripkin
2021-10-23 4:50 ` syzbot
2021-10-23 7:41 ` Sven Eckelmann
2021-10-24 13:13 ` [PATCH] net: batman-adv: fix error handling Pavel Skripkin
2021-10-24 14:58 ` Sven Eckelmann
2021-10-26 0:49 ` Jakub Kicinski [this message]
2021-10-26 6:51 ` Sven Eckelmann
2021-10-26 13:50 ` patchwork-bot+netdevbpf
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