CVE-2026-23255
Full vulnerability record from the local CVENow database.
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.
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-03-18 18:16:23.687000
Last modified
2026-11-05 22:18:09.283000
View original CVE JSON
{
"id": "CVE-2026-23255",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-03-18T18:16:23.687",
"lastModified": "2026-11-05T22:18:09.283",
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{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: add proper RCU protection to /proc/net/ptype\n\nYin Fengwei reported an RCU stall in ptype_seq_show() and provided\na patch.\n\nReal issue is that ptype_seq_next() and ptype_seq_show() violate\nRCU rules.\n\nptype_seq_show() runs under rcu_read_lock(), and reads pt->dev\nto get device name without any barrier.\n\nAt the same time, concurrent writers can remove a packet_type structure\n(which is correctly freed after an RCU grace period) and clear pt->dev\nwithout an RCU grace period.\n\nDefine ptype_iter_state to carry a dev pointer along seq_net_private:\n\nstruct ptype_iter_state {\n\tstruct seq_net_private\tp;\n\tstruct net_device\t*dev; // added in this patch\n};\n\nWe need to record the device pointer in ptype_get_idx() and\nptype_seq_next() so that ptype_seq_show() is safe against\nconcurrent pt->dev changes.\n\nWe also need to add full RCU protection in ptype_seq_next().\n(Missing READ_ONCE() when reading list.next values)\n\nMany thanks to Dong Chenchen for providing a repro."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet: añadir protección RCU adecuada a /proc/net/ptype\n\nYin Fengwei informó de un bloqueo RCU en ptype_seq_show() y proporcionó un parche.\n\nEl problema real es que ptype_seq_next() y ptype_seq_show() violan las reglas RCU.\n\nptype_seq_show() se ejecuta bajo rcu_read_lock(), y lee pt->dev para obtener el nombre del dispositivo sin ninguna barrera.\n\nAl mismo tiempo, los escritores concurrentes pueden eliminar una estructura packet_type (que se libera correctamente después de un período de gracia RCU) y borrar pt->dev sin un período de gracia RCU.\n\nDefinir ptype_iter_state para llevar un puntero dev junto con seq_net_private:\n\nstruct ptype_iter_state {\n\tstruct seq_net_private\tp;\n\tstruct net_device\t*dev; // añadido en este parche\n};\n\nNecesitamos registrar el puntero del dispositivo en ptype_get_idx() y ptype_seq_next() para que ptype_seq_show() esté a salvo de cambios concurrentes en pt->dev.\n\nTambién necesitamos añadir protección RCU completa en ptype_seq_next().\n(Falta READ_ONCE() al leer los valores de list.next)\n\nMuchas gracias a Dong Chenchen por proporcionar una reproducción."
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