| 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-2024-53186: ksmbd: fix use-after-free in SMB request handling |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| ksmbd: fix use-after-free in SMB request handling |
| |
| A race condition exists between SMB request handling in |
| `ksmbd_conn_handler_loop()` and the freeing of `ksmbd_conn` in the |
| workqueue handler `handle_ksmbd_work()`. This leads to a UAF. |
| - KASAN: slab-use-after-free Read in handle_ksmbd_work |
| - KASAN: slab-use-after-free in rtlock_slowlock_locked |
| |
| This race condition arises as follows: |
| - `ksmbd_conn_handler_loop()` waits for `conn->r_count` to reach zero: |
| `wait_event(conn->r_count_q, atomic_read(&conn->r_count) == 0);` |
| - Meanwhile, `handle_ksmbd_work()` decrements `conn->r_count` using |
| `atomic_dec_return(&conn->r_count)`, and if it reaches zero, calls |
| `ksmbd_conn_free()`, which frees `conn`. |
| - However, after `handle_ksmbd_work()` decrements `conn->r_count`, |
| it may still access `conn->r_count_q` in the following line: |
| `waitqueue_active(&conn->r_count_q)` or `wake_up(&conn->r_count_q)` |
| This results in a UAF, as `conn` has already been freed. |
| |
| The discovery of this UAF can be referenced in the following PR for |
| syzkaller's support for SMB requests. |
| |
| The Linux kernel CVE team has assigned CVE-2024-53186 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6.55 with commit 18f06bacc197d4ac9b518ad1c69999bc3d83e7aa and fixed in 6.6.64 with commit a96f9eb7add30ba0fafcfe7b7aca090978196800 |
| Issue introduced in 6.11.3 with commit e9dac92f4482a382e8c0fe1bc243da5fc3526b0c and fixed in 6.11.11 with commit f20b77f7897e6aab9ce5527e6016ad2be5d70a33 |
| Issue introduced in 6.12 with commit ee426bfb9d09b29987369b897fe9b6485ac2be27 and fixed in 6.12.2 with commit 96261adb998a3b513468b6ce17dbec76be5507d4 |
| Issue introduced in 6.12 with commit ee426bfb9d09b29987369b897fe9b6485ac2be27 and fixed in 6.13 with commit 9a8c5d89d327ff58e9b2517f8a6afb4181d32c6e |
| Issue introduced in 6.10.14 with commit 9fd3cde4628bcd3549ab95061f2bab74d2ed4f3b |
| |
| 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-2024-53186 |
| 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: |
| fs/smb/server/server.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/a96f9eb7add30ba0fafcfe7b7aca090978196800 |
| https://git.kernel.org/stable/c/f20b77f7897e6aab9ce5527e6016ad2be5d70a33 |
| https://git.kernel.org/stable/c/96261adb998a3b513468b6ce17dbec76be5507d4 |
| https://git.kernel.org/stable/c/9a8c5d89d327ff58e9b2517f8a6afb4181d32c6e |
