| 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-2022-49195: net: dsa: fix panic on shutdown if multi-chip tree failed to probe |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| net: dsa: fix panic on shutdown if multi-chip tree failed to probe |
| |
| DSA probing is atypical because a tree of devices must probe all at |
| once, so out of N switches which call dsa_tree_setup_routing_table() |
| during probe, for (N - 1) of them, "complete" will return false and they |
| will exit probing early. The Nth switch will set up the whole tree on |
| their behalf. |
| |
| The implication is that for (N - 1) switches, the driver binds to the |
| device successfully, without doing anything. When the driver is bound, |
| the ->shutdown() method may run. But if the Nth switch has failed to |
| initialize the tree, there is nothing to do for the (N - 1) driver |
| instances, since the slave devices have not been created, etc. Moreover, |
| dsa_switch_shutdown() expects that the calling @ds has been in fact |
| initialized, so it jumps at dereferencing the various data structures, |
| which is incorrect. |
| |
| Avoid the ensuing NULL pointer dereferences by simply checking whether |
| the Nth switch has previously set "ds->setup = true" for the switch |
| which is currently shutting down. The entire setup is serialized under |
| dsa2_mutex which we already hold. |
| |
| The Linux kernel CVE team has assigned CVE-2022-49195 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.15 with commit 0650bf52b31ff35dc6430fc2e37969c36baba724 and fixed in 5.15.33 with commit 95df5cd5a446df6738d2d45872e08594819080e4 |
| Issue introduced in 5.15 with commit 0650bf52b31ff35dc6430fc2e37969c36baba724 and fixed in 5.16.19 with commit b6e668ff43ebd87ccc8a19e5481345c428672295 |
| Issue introduced in 5.15 with commit 0650bf52b31ff35dc6430fc2e37969c36baba724 and fixed in 5.17.2 with commit b864d5350c18bea9369d0bdd9e7eb6f6172cc283 |
| Issue introduced in 5.15 with commit 0650bf52b31ff35dc6430fc2e37969c36baba724 and fixed in 5.18 with commit 8fd36358ce82382519b50b05f437493e1e00c4a9 |
| |
| 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-2022-49195 |
| 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/dsa/dsa2.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/95df5cd5a446df6738d2d45872e08594819080e4 |
| https://git.kernel.org/stable/c/b6e668ff43ebd87ccc8a19e5481345c428672295 |
| https://git.kernel.org/stable/c/b864d5350c18bea9369d0bdd9e7eb6f6172cc283 |
| https://git.kernel.org/stable/c/8fd36358ce82382519b50b05f437493e1e00c4a9 |
