| 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-2021-47293: net/sched: act_skbmod: Skip non-Ethernet packets |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| net/sched: act_skbmod: Skip non-Ethernet packets |
| |
| Currently tcf_skbmod_act() assumes that packets use Ethernet as their L2 |
| protocol, which is not always the case. As an example, for CAN devices: |
| |
| $ ip link add dev vcan0 type vcan |
| $ ip link set up vcan0 |
| $ tc qdisc add dev vcan0 root handle 1: htb |
| $ tc filter add dev vcan0 parent 1: protocol ip prio 10 \ |
| matchall action skbmod swap mac |
| |
| Doing the above silently corrupts all the packets. Do not perform skbmod |
| actions for non-Ethernet packets. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47293 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.9 with commit 86da71b57383d40993cb90baafb3735cffe5d800 and fixed in 4.19.199 with commit e4fdca366806f6bab374d1a95e626a10a3854b0c |
| Issue introduced in 4.9 with commit 86da71b57383d40993cb90baafb3735cffe5d800 and fixed in 5.4.136 with commit a88414fb1117f2fe65fb88e45ba694e1d09d5024 |
| Issue introduced in 4.9 with commit 86da71b57383d40993cb90baafb3735cffe5d800 and fixed in 5.10.54 with commit 071729150be9e1d1b851b70efb6d91ee9269d57b |
| Issue introduced in 4.9 with commit 86da71b57383d40993cb90baafb3735cffe5d800 and fixed in 5.13.6 with commit 34f1e1f657fae2891b485a3b2b95fe4d2aef9f0d |
| Issue introduced in 4.9 with commit 86da71b57383d40993cb90baafb3735cffe5d800 and fixed in 5.14 with commit 727d6a8b7ef3d25080fad228b2c4a1d4da5999c6 |
| |
| 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-2021-47293 |
| 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/act_skbmod.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/e4fdca366806f6bab374d1a95e626a10a3854b0c |
| https://git.kernel.org/stable/c/a88414fb1117f2fe65fb88e45ba694e1d09d5024 |
| https://git.kernel.org/stable/c/071729150be9e1d1b851b70efb6d91ee9269d57b |
| https://git.kernel.org/stable/c/34f1e1f657fae2891b485a3b2b95fe4d2aef9f0d |
| https://git.kernel.org/stable/c/727d6a8b7ef3d25080fad228b2c4a1d4da5999c6 |
