| From bippy-a5840b7849dd 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-2021-47581: xen/netback: don't queue unlimited number of packages |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| xen/netback: don't queue unlimited number of packages |
| |
| In case a guest isn't consuming incoming network traffic as fast as it |
| is coming in, xen-netback is buffering network packages in unlimited |
| numbers today. This can result in host OOM situations. |
| |
| Commit f48da8b14d04ca8 ("xen-netback: fix unlimited guest Rx internal |
| queue and carrier flapping") meant to introduce a mechanism to limit |
| the amount of buffered data by stopping the Tx queue when reaching the |
| data limit, but this doesn't work for cases like UDP. |
| |
| When hitting the limit don't queue further SKBs, but drop them instead. |
| In order to be able to tell Rx packages have been dropped increment the |
| rx_dropped statistics counter in this case. |
| |
| It should be noted that the old solution to continue queueing SKBs had |
| the additional problem of an overflow of the 32-bit rx_queue_len value |
| would result in intermittent Tx queue enabling. |
| |
| This is part of XSA-392 |
| |
| The Linux kernel CVE team has assigned CVE-2021-47581 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 3.18 with commit f48da8b14d04 and fixed in 4.4.296 with commit 0928efb09178 |
| Issue introduced in 3.18 with commit f48da8b14d04 and fixed in 4.9.294 with commit b4226b387436 |
| Issue introduced in 3.18 with commit f48da8b14d04 and fixed in 4.14.259 with commit 9bebb2eedf67 |
| Issue introduced in 3.18 with commit f48da8b14d04 and fixed in 4.19.222 with commit c9f17e92917f |
| Issue introduced in 3.18 with commit f48da8b14d04 and fixed in 5.4.168 with commit 0d99b3c6bd39 |
| Issue introduced in 3.18 with commit f48da8b14d04 and fixed in 5.10.88 with commit 88f20cccbeec |
| Issue introduced in 3.18 with commit f48da8b14d04 and fixed in 5.15.11 with commit bd926d189210 |
| Issue introduced in 3.18 with commit f48da8b14d04 and fixed in 5.16 with commit be81992f9086 |
| |
| 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-2021-47581 |
| 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/xen-netback/rx.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/0928efb09178e01d3dc8e8849aa1c807436c3c37 |
| https://git.kernel.org/stable/c/b4226b387436315e7f57465c15335f4f4b5b075d |
| https://git.kernel.org/stable/c/9bebb2eedf679b3be4acaa20efda97f32c999d74 |
| https://git.kernel.org/stable/c/c9f17e92917fd5786be872626a3928979ecc4c39 |
| https://git.kernel.org/stable/c/0d99b3c6bd39a0a023e972d8f912fd47698bbbb8 |
| https://git.kernel.org/stable/c/88f20cccbeec9a5e83621df5cc2453b5081454dc |
| https://git.kernel.org/stable/c/bd926d189210cd1d5b4e618e45898053be6b4b3b |
| https://git.kernel.org/stable/c/be81992f9086b230623ae3ebbc85ecee4d00a3d3 |
