CVE-2025-39673 In the Linux kernel, the following vulnerability has been resolved: ppp: fix race conditions in ppp_fill_forward_path…
Description
In the Linux kernel, the following vulnerability has been resolved: ppp: fix race conditions in ppp_fill_forward_path ppp_fill_forward_path() has two race conditions: 1. The ppp->channels list can change between list_empty() and list_first_entry(), as ppp_lock() is not held. If the only channel is deleted in ppp_disconnect_channel(), list_first_entry() may access an empty head or a freed entry, and trigger a panic. 2. pch->chan can be NULL. When ppp_unregister_channel() is called, pch->chan is set to NULL before pch is removed from ppp->channels. Fix these by using a lockless RCU approach: - Use list_first_or_null_rcu() to safely test and access the first list entry. - Convert list modifications on ppp->channels to their RCU variants and add synchronize_net() after removal. - Check for a NULL pch->chan before dereferencing it.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux 6.17 | earliest → < 6.17 | 6.17 |
| Linux 6.16 | earliest → < 6.16.4 | 6.16.4 |
| Linux 6.12 | earliest → < 6.12.44 | 6.12.44 |
| Linux 6.6 | earliest → < 6.6.103 | 6.6.103 |
| Linux 6.1 | earliest → < 6.1.149 | 6.1.149 |
| Linux 5.15 | earliest → < 5.15.190 | 5.15.190 |
| Linux | 5.13 | No fix stated |
| SIMATIC CN 4100 5.0 | earliest → < 5.0 | 5.0 |
References
- git.kernel.org git.kernel.org
- git.kernel.org git.kernel.org
- git.kernel.org git.kernel.org
- git.kernel.org git.kernel.org
- git.kernel.org git.kernel.org
- git.kernel.org git.kernel.org
Timeline
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