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Date: Mon, 25 Oct 2021 17:49:50 -0700 From: Jakub Kicinski <kuba@...nel.org> To: Sven Eckelmann <sven@...fation.org>, mareklindner@...mailbox.ch Cc: sw@...onwunderlich.de, a@...table.cc, davem@...emloft.net, Pavel Skripkin <paskripkin@...il.com>, b.a.t.m.a.n@...ts.open-mesh.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, syzbot+28b0702ada0bf7381f58@...kaller.appspotmail.com Subject: Re: [PATCH] net: batman-adv: fix error handling 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@...kaller.appspotmail.com > > Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol") > > Signed-off-by: Pavel Skripkin <paskripkin@...il.com> > > Acked-by: Sven Eckelmann <sven@...fation.org> FWIW I'm marking this as "Awaiting upstream" in netdev patchwork, please LMK if you prefer for it to be applied directly.
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