| 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-2021-47225: mac80211: fix deadlock in AP/VLAN handling |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mac80211: fix deadlock in AP/VLAN handling |
| |
| Syzbot reports that when you have AP_VLAN interfaces that are up |
| and close the AP interface they belong to, we get a deadlock. No |
| surprise - since we dev_close() them with the wiphy mutex held, |
| which goes back into the netdev notifier in cfg80211 and tries to |
| acquire the wiphy mutex there. |
| |
| To fix this, we need to do two things: |
| 1) prevent changing iftype while AP_VLANs are up, we can't |
| easily fix this case since cfg80211 already calls us with |
| the wiphy mutex held, but change_interface() is relatively |
| rare in drivers anyway, so changing iftype isn't used much |
| (and userspace has to fall back to down/change/up anyway) |
| 2) pull the dev_close() loop over VLANs out of the wiphy mutex |
| section in the normal stop case |
| |
| The Linux kernel CVE team has assigned CVE-2021-47225 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.12 with commit a05829a7222e9d10c416dd2dbbf3929fe6646b89 and fixed in 5.12.13 with commit 8043903fcb72f545c52e3ec74d6fd82ef79ce7c5 |
| Issue introduced in 5.12 with commit a05829a7222e9d10c416dd2dbbf3929fe6646b89 and fixed in 5.13 with commit d5befb224edbe53056c2c18999d630dafb4a08b9 |
| |
| 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-2021-47225 |
| 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/mac80211/iface.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/8043903fcb72f545c52e3ec74d6fd82ef79ce7c5 |
| https://git.kernel.org/stable/c/d5befb224edbe53056c2c18999d630dafb4a08b9 |
