| 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-2024-26998: serial: core: Clearing the circular buffer before NULLifying it |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| serial: core: Clearing the circular buffer before NULLifying it |
| |
| The circular buffer is NULLified in uart_tty_port_shutdown() |
| under the spin lock. However, the PM or other timer based callbacks |
| may still trigger after this event without knowning that buffer pointer |
| is not valid. Since the serial code is a bit inconsistent in checking |
| the buffer state (some rely on the head-tail positions, some on the |
| buffer pointer), it's better to have both aligned, i.e. buffer pointer |
| to be NULL and head-tail possitions to be the same, meaning it's empty. |
| This will prevent asynchronous calls to dereference NULL pointer as |
| reported recently in 8250 case: |
| |
| BUG: kernel NULL pointer dereference, address: 00000cf5 |
| Workqueue: pm pm_runtime_work |
| EIP: serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809) |
| ... |
| ? serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809) |
| __start_tx (drivers/tty/serial/8250/8250_port.c:1551) |
| serial8250_start_tx (drivers/tty/serial/8250/8250_port.c:1654) |
| serial_port_runtime_suspend (include/linux/serial_core.h:667 drivers/tty/serial/serial_port.c:63) |
| __rpm_callback (drivers/base/power/runtime.c:393) |
| ? serial_port_remove (drivers/tty/serial/serial_port.c:50) |
| rpm_suspend (drivers/base/power/runtime.c:447) |
| |
| The proposed change will prevent ->start_tx() to be called during |
| suspend on shut down port. |
| |
| The Linux kernel CVE team has assigned CVE-2024-26998 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6.24 with commit 434beb66368d4fb4d3119c2116b9398500adbf47 and fixed in 6.6.29 with commit 7ae7104d54342433a3a73975f6569beefdd86350 |
| Issue introduced in 6.8 with commit 43066e32227ecde674e8ae1fcdd4a1ede67680c2 and fixed in 6.8.8 with commit bb1118905e875c111d7ccef9aee86ac5e4e7f985 |
| Issue introduced in 6.8 with commit 43066e32227ecde674e8ae1fcdd4a1ede67680c2 and fixed in 6.9 with commit 9cf7ea2eeb745213dc2a04103e426b960e807940 |
| Issue introduced in 6.7.12 with commit a629a9b2f7699314a4abe8fbc37b0ee667b60f33 |
| |
| 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-2024-26998 |
| 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/tty/serial/serial_core.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/7ae7104d54342433a3a73975f6569beefdd86350 |
| https://git.kernel.org/stable/c/bb1118905e875c111d7ccef9aee86ac5e4e7f985 |
| https://git.kernel.org/stable/c/9cf7ea2eeb745213dc2a04103e426b960e807940 |
