| From bippy-7c5fe7eed585 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-2025-21926: net: gso: fix ownership in __udp_gso_segment |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| net: gso: fix ownership in __udp_gso_segment |
| |
| In __udp_gso_segment the skb destructor is removed before segmenting the |
| skb but the socket reference is kept as-is. This is an issue if the |
| original skb is later orphaned as we can hit the following bug: |
| |
| kernel BUG at ./include/linux/skbuff.h:3312! (skb_orphan) |
| RIP: 0010:ip_rcv_core+0x8b2/0xca0 |
| Call Trace: |
| ip_rcv+0xab/0x6e0 |
| __netif_receive_skb_one_core+0x168/0x1b0 |
| process_backlog+0x384/0x1100 |
| __napi_poll.constprop.0+0xa1/0x370 |
| net_rx_action+0x925/0xe50 |
| |
| The above can happen following a sequence of events when using |
| OpenVSwitch, when an OVS_ACTION_ATTR_USERSPACE action precedes an |
| OVS_ACTION_ATTR_OUTPUT action: |
| |
| 1. OVS_ACTION_ATTR_USERSPACE is handled (in do_execute_actions): the skb |
| goes through queue_gso_packets and then __udp_gso_segment, where its |
| destructor is removed. |
| 2. The segments' data are copied and sent to userspace. |
| 3. OVS_ACTION_ATTR_OUTPUT is handled (in do_execute_actions) and the |
| same original skb is sent to its path. |
| 4. If it later hits skb_orphan, we hit the bug. |
| |
| Fix this by also removing the reference to the socket in |
| __udp_gso_segment. |
| |
| The Linux kernel CVE team has assigned CVE-2025-21926 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.18 with commit ad405857b174ed31a97982bb129c320d03321cf5 and fixed in 5.4.291 with commit 9f28205ddb76e86cac418332e952241d85fed0dc |
| Issue introduced in 4.18 with commit ad405857b174ed31a97982bb129c320d03321cf5 and fixed in 5.10.235 with commit a2d1cca955ed34873e524cc2e6e885450d262f05 |
| Issue introduced in 4.18 with commit ad405857b174ed31a97982bb129c320d03321cf5 and fixed in 5.15.179 with commit 455217ac9db0cf9349b3933664355e907bb1a569 |
| Issue introduced in 4.18 with commit ad405857b174ed31a97982bb129c320d03321cf5 and fixed in 6.1.131 with commit e8db70537878e1bb3fd83e5abcc6feefc0587828 |
| Issue introduced in 4.18 with commit ad405857b174ed31a97982bb129c320d03321cf5 and fixed in 6.6.83 with commit 01a83237644d6822bc7df2c5564fc81b0df84358 |
| Issue introduced in 4.18 with commit ad405857b174ed31a97982bb129c320d03321cf5 and fixed in 6.12.19 with commit 084819b0d8b1bd433b90142371eb9450d657f8ca |
| Issue introduced in 4.18 with commit ad405857b174ed31a97982bb129c320d03321cf5 and fixed in 6.13.7 with commit c32da44cc9298eaa6109e3fc2c2b4e07cc4bf11b |
| Issue introduced in 4.18 with commit ad405857b174ed31a97982bb129c320d03321cf5 and fixed in 6.14 with commit ee01b2f2d7d0010787c2343463965bbc283a497f |
| |
| 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-2025-21926 |
| 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/ipv4/udp_offload.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/9f28205ddb76e86cac418332e952241d85fed0dc |
| https://git.kernel.org/stable/c/a2d1cca955ed34873e524cc2e6e885450d262f05 |
| https://git.kernel.org/stable/c/455217ac9db0cf9349b3933664355e907bb1a569 |
| https://git.kernel.org/stable/c/e8db70537878e1bb3fd83e5abcc6feefc0587828 |
| https://git.kernel.org/stable/c/01a83237644d6822bc7df2c5564fc81b0df84358 |
| https://git.kernel.org/stable/c/084819b0d8b1bd433b90142371eb9450d657f8ca |
| https://git.kernel.org/stable/c/c32da44cc9298eaa6109e3fc2c2b4e07cc4bf11b |
| https://git.kernel.org/stable/c/ee01b2f2d7d0010787c2343463965bbc283a497f |
