On Tue, Nov 16, 2021 at 11:50:28AM +0100, Simon Wunderlich wrote:
From: Pavel Skripkin paskripkin@gmail.com
commit 6f68cd634856f8ca93bafd623ba5357e0f648c68 upstream.
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 Signed-off-by: David S. Miller davem@davemloft.net [ bp: 4.4 backport: Drop batadv_v_mesh_{init,free} which are not there yet. ] Signed-off-by: Sven Eckelmann sven@narfation.org
Submission according to the request in https://lore.kernel.org/all/163559888490194@kroah.com/
Now queued up, thanks.
greg k-h