CVE-2021-47482: net: batman-adv: fix error handling
First published: Wed May 22 2024(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| Linux Kernel | >=2.6.38<4.4.293 | |
| Linux Kernel | >=4.5<4.9.289 | |
| Linux Kernel | >=4.10<4.14.254 | |
| Linux Kernel | >=4.15<4.19.215 | |
| Linux Kernel | >=4.20<5.4.157 | |
| Linux Kernel | >=5.5<5.10.77 | |
| Linux Kernel | >=5.11<5.14.16 | |
| Linux Kernel | =5.15-rc1 | |
| Linux Kernel | =5.15-rc2 | |
| Linux Kernel | =5.15-rc3 | |
| Linux Kernel | =5.15-rc4 | |
| Linux Kernel | =5.15-rc5 | |
| Linux Kernel | =5.15-rc6 | |
| Linux Kernel | =5.15-rc7 |
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Reference Links
- https://git.kernel.org/stable/c/0c6b199f09be489c48622537a550787fc80aea73
- https://git.kernel.org/stable/c/07533f1a673ce1126d0a72ef1e4b5eaaa3dd6d20
- https://git.kernel.org/stable/c/e50f957652190b5a88a8ebce7e5ab14ebd0d3f00
- https://git.kernel.org/stable/c/fbf150b16a3635634b7dfb7f229d8fcd643c6c51
- https://git.kernel.org/stable/c/6422e8471890273994fe8cc6d452b0dcd2c9483e
- https://git.kernel.org/stable/c/b0a2cd38553c77928ef1646ed1518486b1e70ae8
- https://git.kernel.org/stable/c/a8f7359259dd5923adc6129284fdad12fc5db347
- https://git.kernel.org/stable/c/6f68cd634856f8ca93bafd623ba5357e0f648c68
Frequently Asked Questions
What is the severity of CVE-2021-47482?
CVE-2021-47482 has been classified as a medium severity vulnerability due to improper error handling in the Linux kernel.
How do I fix CVE-2021-47482?
To fix CVE-2021-47482, you should apply the latest patches or updates provided by your Linux distribution's repository.
What systems are affected by CVE-2021-47482?
CVE-2021-47482 affects systems running the Linux kernel that utilize the batman-adv networking protocol.
What type of vulnerability is CVE-2021-47482?
CVE-2021-47482 is an error handling vulnerability in the batman-adv module of the Linux kernel.
Who reported the CVE-2021-47482 vulnerability?
The CVE-2021-47482 vulnerability was reported by the Syzbot automated testing system.
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