Yin Fengwei

**Name of the Vulnerable Software and Affected Versions** Linux kernel (affected versions not specified) **Description** The Linux kernel contains a flaw related to RCU (Read-Copy-Update) protection in the `/proc/net/ptype` interface. Specifically, the functions `ptype seq next()` and `ptype seq show()` do not adhere to RCU rules, potentially leading to RCU stalls. The issue arises because `ptype seq show()` reads `pt->dev` to obtain the device name without proper synchronization, while concurrent writers can remove packet type structures and clear `pt->dev` without an RCU grace period. The fix involves defining `ptype iter state` to carry a device pointer and adding full RCU protection to `ptype seq next()`, including the use of `READ ONCE()` when reading `list.next` values. A reproduction of the issue was provided by Dong Chenchen. **Recommendations** At the moment, there is no information about a newer version that contains a fix for this vulnerability.