CVE-2021-47482

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

net: batman-adv: fix error handling

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

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References