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Debian: CVE-2021-47482: linux -- security update

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Debian: CVE-2021-47482: linux -- security update

Severity
4
CVSS
(AV:L/AC:M/Au:N/C:P/I:P/A:P)
Published
05/22/2024
Created
07/31/2024
Added
07/30/2024
Modified
07/30/2024

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 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.

Solution(s)

  • debian-upgrade-linux

References

  • https://attackerkb.com/topics/cve-2021-47482
  • CVE - 2021-47482
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