Description
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 ptype_seq_show() and provided a patch. Real issue is that ptype_seq_next() and ptype_seq_show() violate RCU rules. ptype_seq_show() runs under rcu_read_lock(), and reads pt->dev to get device name without any barrier. At the same time, concurrent writers can remove a packet_type structure (which is correctly freed after an RCU grace period) and clear pt->dev without an RCU grace period. Define ptype_iter_state to carry a dev pointer along seq_net_private: struct ptype_iter_state { struct seq_net_private p; struct net_device *dev; // added in this patch }; We need to record the device pointer in ptype_get_idx() and ptype_seq_next() so that ptype_seq_show() is safe against concurrent pt->dev changes. We also need to add full RCU protection in ptype_seq_next(). (Missing READ_ONCE() when reading list.next values) Many thanks to Dong Chenchen for providing a repro.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < e974a10a52618f7f57a4bce173a0ed96acd4e5dcaffected1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 002a73470b56848e4c81efeaaedd471e92d66d8daffected1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < dcefd3f0b9ed8288654c75254bdcee8e1085e861affected1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 589a530ae44d0c80f523fcfd1a15af8087f27d35affected1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < f613e8b4afea0cd17c7168e8b00e25bc8d33175daffected
Linux Linux
Default version status: affected
2.6.12affected0 to < 2.6.12unaffected6.1.175 to ≤ 6.1.*unaffected6.6.136 to ≤ 6.6.*unaffected6.12.80 to ≤ 6.12.*unaffected6.18.10 to ≤ 6.18.*unaffected6.19 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/e974a10a52618f7f57a4bce173a0ed96acd4e5dc ↗
- https://git.kernel.org/stable/c/002a73470b56848e4c81efeaaedd471e92d66d8d ↗
- https://git.kernel.org/stable/c/dcefd3f0b9ed8288654c75254bdcee8e1085e861 ↗
- https://git.kernel.org/stable/c/589a530ae44d0c80f523fcfd1a15af8087f27d35 ↗
- https://git.kernel.org/stable/c/f613e8b4afea0cd17c7168e8b00e25bc8d33175d ↗
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-784472.html ↗