In the Linux kernel, the following vulnerability has been resolved: net: add proper RCU protection to /proc/net/ptype Yin Fengwei reported an RCU stall in ptypeseqshow() and provided a patch. Real issue is that ptypeseqnext() and ptypeseqshow() violate RCU rules. ptypeseqshow() runs under rcureadlock(), and reads pt->dev to get device name without any barrier. At the same time, concurrent writers can remove a packettype structure (which is correctly freed after an RCU grace period) and clear pt->dev without an RCU grace period. Define ptypeiterstate to carry a dev pointer along seqnetprivate: struct ptypeiterstate { struct seqnetprivate p; struct netdevice *dev; // added in this patch }; We need to record the device pointer in ptypegetidx() and ptypeseqnext() so that ptypeseqshow() is safe against concurrent pt->dev changes. We also need to add full RCU protection in ptypeseqnext(). (Missing READ_ONCE() when reading list.next values) Many thanks to Dong Chenchen for providing a repro.