CVE-2021-47482: Linux Kernel

Medium severity, CVSS 5.3. EPSS: 0.7% chance of exploitation in the next 30 days.

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 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.

Affected products

• Linux Linux Kernel: from 2.6.38, before 4.4.293 (fixed in 4.4.293); from 4.5, before 4.9.289 (fixed in 4.9.289); from 4.10, before 4.14.254 (fixed in 4.14.254); from 4.15, before 4.19.215 (fixed in 4.19.215); from 4.20, before 5.4.157 (fixed in 5.4.157); from 5.5, before 5.10.77 (fixed in 5.10.77); …

Published 2024-05-22. Last modified 2026-06-17.