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. 
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://email@example.com/  Reported-and-tested-by: firstname.lastname@example.org Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol") Signed-off-by: Pavel Skripkin email@example.com
Acked-by: Sven Eckelmann firstname.lastname@example.org
FWIW I'm marking this as "Awaiting upstream" in netdev patchwork, please LMK if you prefer for it to be applied directly.