| 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-2021-47243: sch_cake: Fix out of bounds when parsing TCP options and header |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| sch_cake: Fix out of bounds when parsing TCP options and header |
| |
| The TCP option parser in cake qdisc (cake_get_tcpopt and |
| cake_tcph_may_drop) could read one byte out of bounds. When the length |
| is 1, the execution flow gets into the loop, reads one byte of the |
| opcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads |
| one more byte, which exceeds the length of 1. |
| |
| This fix is inspired by commit 9609dad263f8 ("ipv4: tcp_input: fix stack |
| out of bounds when parsing TCP options."). |
| |
| v2 changes: |
| |
| Added doff validation in cake_get_tcphdr to avoid parsing garbage as TCP |
| header. Although it wasn't strictly an out-of-bounds access (memory was |
| allocated), garbage values could be read where CAKE expected the TCP |
| header if doff was smaller than 5. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47243 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.19 with commit 8b7138814f29933898ecd31dfc83e35a30ee69f5 and fixed in 4.19.196 with commit 595897ef118d6fe66690c4fc5b572028c9da95b7 |
| Issue introduced in 4.19 with commit 8b7138814f29933898ecd31dfc83e35a30ee69f5 and fixed in 5.4.128 with commit 4cefa061fc63f4d2dff5ab4083f43857cd7a2335 |
| Issue introduced in 4.19 with commit 8b7138814f29933898ecd31dfc83e35a30ee69f5 and fixed in 5.10.46 with commit 3b491dd593d582ceeb27aa617600712a6bd14246 |
| Issue introduced in 4.19 with commit 8b7138814f29933898ecd31dfc83e35a30ee69f5 and fixed in 5.12.13 with commit 3371392c60e2685af30bd4547badd880f5df2b3f |
| Issue introduced in 4.19 with commit 8b7138814f29933898ecd31dfc83e35a30ee69f5 and fixed in 5.13 with commit ba91c49dedbde758ba0b72f57ac90b06ddf8e548 |
| |
| 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-2021-47243 |
| 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/sch_cake.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/595897ef118d6fe66690c4fc5b572028c9da95b7 |
| https://git.kernel.org/stable/c/4cefa061fc63f4d2dff5ab4083f43857cd7a2335 |
| https://git.kernel.org/stable/c/3b491dd593d582ceeb27aa617600712a6bd14246 |
| https://git.kernel.org/stable/c/3371392c60e2685af30bd4547badd880f5df2b3f |
| https://git.kernel.org/stable/c/ba91c49dedbde758ba0b72f57ac90b06ddf8e548 |
