| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-21806: net: let net.core.dev_weight always be non-zero |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| net: let net.core.dev_weight always be non-zero |
| |
| The following problem was encountered during stability test: |
| |
| (NULL net_device): NAPI poll function process_backlog+0x0/0x530 \ |
| returned 1, exceeding its budget of 0. |
| ------------[ cut here ]------------ |
| list_add double add: new=ffff88905f746f48, prev=ffff88905f746f48, \ |
| next=ffff88905f746e40. |
| WARNING: CPU: 18 PID: 5462 at lib/list_debug.c:35 \ |
| __list_add_valid_or_report+0xf3/0x130 |
| CPU: 18 UID: 0 PID: 5462 Comm: ping Kdump: loaded Not tainted 6.13.0-rc7+ |
| RIP: 0010:__list_add_valid_or_report+0xf3/0x130 |
| Call Trace: |
| ? __warn+0xcd/0x250 |
| ? __list_add_valid_or_report+0xf3/0x130 |
| enqueue_to_backlog+0x923/0x1070 |
| netif_rx_internal+0x92/0x2b0 |
| __netif_rx+0x15/0x170 |
| loopback_xmit+0x2ef/0x450 |
| dev_hard_start_xmit+0x103/0x490 |
| __dev_queue_xmit+0xeac/0x1950 |
| ip_finish_output2+0x6cc/0x1620 |
| ip_output+0x161/0x270 |
| ip_push_pending_frames+0x155/0x1a0 |
| raw_sendmsg+0xe13/0x1550 |
| __sys_sendto+0x3bf/0x4e0 |
| __x64_sys_sendto+0xdc/0x1b0 |
| do_syscall_64+0x5b/0x170 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| The reproduction command is as follows: |
| sysctl -w net.core.dev_weight=0 |
| ping 127.0.0.1 |
| |
| This is because when the napi's weight is set to 0, process_backlog() may |
| return 0 and clear the NAPI_STATE_SCHED bit of napi->state, causing this |
| napi to be re-polled in net_rx_action() until __do_softirq() times out. |
| Since the NAPI_STATE_SCHED bit has been cleared, napi_schedule_rps() can |
| be retriggered in enqueue_to_backlog(), causing this issue. |
| |
| Making the napi's weight always non-zero solves this problem. |
| |
| Triggering this issue requires system-wide admin (setting is |
| not namespaced). |
| |
| The Linux kernel CVE team has assigned CVE-2025-21806 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 2.6.12 with commit e3876605450979fe52a1a03e7eb78a89bf59e76a and fixed in 5.4.291 with commit d0e0f9c8218826926d7692980c98236d9f21fd3c |
| Issue introduced in 2.6.12 with commit e3876605450979fe52a1a03e7eb78a89bf59e76a and fixed in 5.10.235 with commit c337c08819a4ec49edfdcd8fc46fbee120d8a5b2 |
| Issue introduced in 2.6.12 with commit e3876605450979fe52a1a03e7eb78a89bf59e76a and fixed in 5.15.179 with commit 0e2f1d93d287d544d26f8ff293ea820a8079b9f8 |
| Issue introduced in 2.6.12 with commit e3876605450979fe52a1a03e7eb78a89bf59e76a and fixed in 6.1.129 with commit 5860abbf15eeb61838b5e32e721ba67b0aa84450 |
| Issue introduced in 2.6.12 with commit e3876605450979fe52a1a03e7eb78a89bf59e76a and fixed in 6.6.76 with commit 6ce38b5a6a49e65bad163162a54cb3f104c40b48 |
| Issue introduced in 2.6.12 with commit e3876605450979fe52a1a03e7eb78a89bf59e76a and fixed in 6.12.13 with commit 33e2168788f8fb5cb8bd4f36cb1ef37d1d34dada |
| Issue introduced in 2.6.12 with commit e3876605450979fe52a1a03e7eb78a89bf59e76a and fixed in 6.13.2 with commit 1489824e5226a26841c70639ebd2d1aed390764b |
| Issue introduced in 2.6.12 with commit e3876605450979fe52a1a03e7eb78a89bf59e76a and fixed in 6.14 with commit d1f9f79fa2af8e3b45cffdeef66e05833480148a |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2025-21806 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| net/core/sysctl_net_core.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/d0e0f9c8218826926d7692980c98236d9f21fd3c |
| https://git.kernel.org/stable/c/c337c08819a4ec49edfdcd8fc46fbee120d8a5b2 |
| https://git.kernel.org/stable/c/0e2f1d93d287d544d26f8ff293ea820a8079b9f8 |
| https://git.kernel.org/stable/c/5860abbf15eeb61838b5e32e721ba67b0aa84450 |
| https://git.kernel.org/stable/c/6ce38b5a6a49e65bad163162a54cb3f104c40b48 |
| https://git.kernel.org/stable/c/33e2168788f8fb5cb8bd4f36cb1ef37d1d34dada |
| https://git.kernel.org/stable/c/1489824e5226a26841c70639ebd2d1aed390764b |
| https://git.kernel.org/stable/c/d1f9f79fa2af8e3b45cffdeef66e05833480148a |
