| 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-2024-39296: bonding: fix oops during rmmod |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| bonding: fix oops during rmmod |
| |
| "rmmod bonding" causes an oops ever since commit cc317ea3d927 ("bonding: |
| remove redundant NULL check in debugfs function"). Here are the relevant |
| functions being called: |
| |
| bonding_exit() |
| bond_destroy_debugfs() |
| debugfs_remove_recursive(bonding_debug_root); |
| bonding_debug_root = NULL; <--------- SET TO NULL HERE |
| bond_netlink_fini() |
| rtnl_link_unregister() |
| __rtnl_link_unregister() |
| unregister_netdevice_many_notify() |
| bond_uninit() |
| bond_debug_unregister() |
| (commit removed check for bonding_debug_root == NULL) |
| debugfs_remove() |
| simple_recursive_removal() |
| down_write() -> OOPS |
| |
| However, reverting the bad commit does not solve the problem completely |
| because the original code contains a race that could cause the same |
| oops, although it was much less likely to be triggered unintentionally: |
| |
| CPU1 |
| rmmod bonding |
| bonding_exit() |
| bond_destroy_debugfs() |
| debugfs_remove_recursive(bonding_debug_root); |
| |
| CPU2 |
| echo -bond0 > /sys/class/net/bonding_masters |
| bond_uninit() |
| bond_debug_unregister() |
| if (!bonding_debug_root) |
| |
| CPU1 |
| bonding_debug_root = NULL; |
| |
| So do NOT revert the bad commit (since the removed checks were racy |
| anyway), and instead change the order of actions taken during module |
| removal. The same oops can also happen if there is an error during |
| module init, so apply the same fix there. |
| |
| The Linux kernel CVE team has assigned CVE-2024-39296 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6 with commit cc317ea3d9272fab4f6fef527c865f30ca479394 and fixed in 6.6.34 with commit f07224c16678a8af54ddc059b3d2d51885d7f35e |
| Issue introduced in 6.6 with commit cc317ea3d9272fab4f6fef527c865f30ca479394 and fixed in 6.9.5 with commit cf48aee81103ca06d09d73d33fb72f1191069aa6 |
| Issue introduced in 6.6 with commit cc317ea3d9272fab4f6fef527c865f30ca479394 and fixed in 6.10 with commit a45835a0bb6ef7d5ddbc0714dd760de979cb6ece |
| |
| 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-2024-39296 |
| 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/bonding/bond_main.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/f07224c16678a8af54ddc059b3d2d51885d7f35e |
| https://git.kernel.org/stable/c/cf48aee81103ca06d09d73d33fb72f1191069aa6 |
| https://git.kernel.org/stable/c/a45835a0bb6ef7d5ddbc0714dd760de979cb6ece |
