| 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-2025-21857: net/sched: cls_api: fix error handling causing NULL dereference |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| net/sched: cls_api: fix error handling causing NULL dereference |
| |
| tcf_exts_miss_cookie_base_alloc() calls xa_alloc_cyclic() which can |
| return 1 if the allocation succeeded after wrapping. This was treated as |
| an error, with value 1 returned to caller tcf_exts_init_ex() which sets |
| exts->actions to NULL and returns 1 to caller fl_change(). |
| |
| fl_change() treats err == 1 as success, calling tcf_exts_validate_ex() |
| which calls tcf_action_init() with exts->actions as argument, where it |
| is dereferenced. |
| |
| Example trace: |
| |
| BUG: kernel NULL pointer dereference, address: 0000000000000000 |
| CPU: 114 PID: 16151 Comm: handler114 Kdump: loaded Not tainted 5.14.0-503.16.1.el9_5.x86_64 #1 |
| RIP: 0010:tcf_action_init+0x1f8/0x2c0 |
| Call Trace: |
| tcf_action_init+0x1f8/0x2c0 |
| tcf_exts_validate_ex+0x175/0x190 |
| fl_change+0x537/0x1120 [cls_flower] |
| |
| The Linux kernel CVE team has assigned CVE-2025-21857 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.3 with commit 80cd22c35c9001fe72bf614d29439de41933deca and fixed in 6.6.80 with commit de4b679aa3b4da7ec34f639df068b914f20e3c3c |
| Issue introduced in 6.3 with commit 80cd22c35c9001fe72bf614d29439de41933deca and fixed in 6.12.17 with commit 3e4c56cf41876ef2a82f0877fe2a67648f8632b8 |
| Issue introduced in 6.3 with commit 80cd22c35c9001fe72bf614d29439de41933deca and fixed in 6.13.5 with commit 3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a |
| Issue introduced in 6.3 with commit 80cd22c35c9001fe72bf614d29439de41933deca and fixed in 6.14 with commit 071ed42cff4fcdd89025d966d48eabef59913bf2 |
| |
| 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-2025-21857 |
| 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/sched/cls_api.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/de4b679aa3b4da7ec34f639df068b914f20e3c3c |
| https://git.kernel.org/stable/c/3e4c56cf41876ef2a82f0877fe2a67648f8632b8 |
| https://git.kernel.org/stable/c/3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a |
| https://git.kernel.org/stable/c/071ed42cff4fcdd89025d966d48eabef59913bf2 |
