| 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-2021-47556: ethtool: ioctl: fix potential NULL deref in ethtool_set_coalesce() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| ethtool: ioctl: fix potential NULL deref in ethtool_set_coalesce() |
| |
| ethtool_set_coalesce() now uses both the .get_coalesce() and |
| .set_coalesce() callbacks. But the check for their availability is |
| buggy, so changing the coalesce settings on a device where the driver |
| provides only _one_ of the callbacks results in a NULL pointer |
| dereference instead of an -EOPNOTSUPP. |
| |
| Fix the condition so that the availability of both callbacks is |
| ensured. This also matches the netlink code. |
| |
| Note that reproducing this requires some effort - it only affects the |
| legacy ioctl path, and needs a specific combination of driver options: |
| - have .get_coalesce() and .coalesce_supported but no |
| .set_coalesce(), or |
| - have .set_coalesce() but no .get_coalesce(). Here eg. ethtool doesn't |
| cause the crash as it first attempts to call ethtool_get_coalesce() |
| and bails out on error. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47556 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.15 with commit f3ccfda1931977b80267ba54070a1aeafa18f6ca and fixed in 5.15.6 with commit abfdd9e2f0f9699015d72317f74154d3e53664e6 |
| Issue introduced in 5.15 with commit f3ccfda1931977b80267ba54070a1aeafa18f6ca and fixed in 5.16 with commit 0276af2176c78771da7f311621a25d7608045827 |
| |
| 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-2021-47556 |
| 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/ethtool/ioctl.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/abfdd9e2f0f9699015d72317f74154d3e53664e6 |
| https://git.kernel.org/stable/c/0276af2176c78771da7f311621a25d7608045827 |
