| From bippy-1.2.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-37921: vxlan: vnifilter: Fix unlocked deletion of default FDB entry |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| vxlan: vnifilter: Fix unlocked deletion of default FDB entry |
| |
| When a VNI is deleted from a VXLAN device in 'vnifilter' mode, the FDB |
| entry associated with the default remote (assuming one was configured) |
| is deleted without holding the hash lock. This is wrong and will result |
| in a warning [1] being generated by the lockdep annotation that was |
| added by commit ebe642067455 ("vxlan: Create wrappers for FDB lookup"). |
| |
| Reproducer: |
| |
| # ip link add vx0 up type vxlan dstport 4789 external vnifilter local 192.0.2.1 |
| # bridge vni add vni 10010 remote 198.51.100.1 dev vx0 |
| # bridge vni del vni 10010 dev vx0 |
| |
| Fix by acquiring the hash lock before the deletion and releasing it |
| afterwards. Blame the original commit that introduced the issue rather |
| than the one that exposed it. |
| |
| [1] |
| WARNING: CPU: 3 PID: 392 at drivers/net/vxlan/vxlan_core.c:417 vxlan_find_mac+0x17f/0x1a0 |
| [...] |
| RIP: 0010:vxlan_find_mac+0x17f/0x1a0 |
| [...] |
| Call Trace: |
| <TASK> |
| __vxlan_fdb_delete+0xbe/0x560 |
| vxlan_vni_delete_group+0x2ba/0x940 |
| vxlan_vni_del.isra.0+0x15f/0x580 |
| vxlan_process_vni_filter+0x38b/0x7b0 |
| vxlan_vnifilter_process+0x3bb/0x510 |
| rtnetlink_rcv_msg+0x2f7/0xb70 |
| netlink_rcv_skb+0x131/0x360 |
| netlink_unicast+0x426/0x710 |
| netlink_sendmsg+0x75a/0xc20 |
| __sock_sendmsg+0xc1/0x150 |
| ____sys_sendmsg+0x5aa/0x7b0 |
| ___sys_sendmsg+0xfc/0x180 |
| __sys_sendmsg+0x121/0x1b0 |
| do_syscall_64+0xbb/0x1d0 |
| entry_SYSCALL_64_after_hwframe+0x4b/0x53 |
| |
| The Linux kernel CVE team has assigned CVE-2025-37921 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.18 with commit f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and fixed in 6.1.138 with commit 2d4a121296aa3940d2df9906f955c2b6b4e38bc3 |
| Issue introduced in 5.18 with commit f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and fixed in 6.6.90 with commit 3576e9a80b6c4381b01ce0cbaa07f5e92d4492ed |
| Issue introduced in 5.18 with commit f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and fixed in 6.12.28 with commit 5cb9e07f84e527974b12e82e2549fa6c0cc6eef0 |
| Issue introduced in 5.18 with commit f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and fixed in 6.14.6 with commit 470206205588559e60035fceb5f256640cb45f99 |
| Issue introduced in 5.18 with commit f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and fixed in 6.15 with commit 087a9eb9e5978e3ba362e1163691e41097e8ca20 |
| |
| 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-2025-37921 |
| 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: |
| drivers/net/vxlan/vxlan_vnifilter.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/2d4a121296aa3940d2df9906f955c2b6b4e38bc3 |
| https://git.kernel.org/stable/c/3576e9a80b6c4381b01ce0cbaa07f5e92d4492ed |
| https://git.kernel.org/stable/c/5cb9e07f84e527974b12e82e2549fa6c0cc6eef0 |
| https://git.kernel.org/stable/c/470206205588559e60035fceb5f256640cb45f99 |
| https://git.kernel.org/stable/c/087a9eb9e5978e3ba362e1163691e41097e8ca20 |
