[PATCH 5.10.y 2/2] serial: imx: serialize imx_uart_ports[] lifetime
DORMANTno replies
REVIEWED: 13 (13M)
From: Sasha Levin <sashal@kernel.org>
Date: 2026-09-04 14:23:19
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
1 review trailer.
From: Karl Mehltretter <redacted>
[ Upstream commit 8b0b29fdcb47907ae0296b8fe829e918e05e300f ]
imx_uart_probe() publishes its devm-allocated port in imx_uart_ports[]
before uart_add_one_port() because console setup uses the table. The entry
is not cleared when adding the port fails or after removal, leaving a
dangling pointer.
A sibling probe can register the shared console through that stale entry.
This was reproduced under KASAN on QEMU mcimx6ul-evk by unbinding a
sibling UART, unbinding the console UART and rebinding the sibling.
Keep the entry valid through uart_remove_one_port(), then clear it. Protect
port addition and removal together with their table updates so sibling
operations cannot interleave. Reject an occupied slot rather than
clobbering an active port during a duplicate-line probe.
Fixes: dbff4e9ea2e8 ("IMX UART: remove statically initialized tables")
Fixes: 9f322ad064f9 ("imx: serial: handle initialisation failure correctly")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://lore.kernel.org/all/20260719162850.043B41F000E9@smtp.kernel.org (local)
Link: https://lore.kernel.org/all/20260719222501.CB4CB1F000E9@smtp.kernel.org (local)
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-fable-5
Signed-off-by: Karl Mehltretter <redacted>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260731181844.11330-6-kmehltretter@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ replaced guard() and scoped_guard() with explicit mutex_lock() and mutex_unlock() calls for GNU89 compatibility. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/imx.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index b558cee2966f3..329b72f648fa3 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c@@ -21,6 +21,7 @@ #include <linux/clk.h> #include <linux/delay.h> #include <linux/ktime.h> +#include <linux/mutex.h> #include <linux/pinctrl/consumer.h> #include <linux/rational.h> #include <linux/slab.h>
@@ -1987,6 +1988,9 @@ static const struct uart_ops imx_uart_pops = { static struct imx_port *imx_uart_ports[UART_NR]; +/* Held across uart_add/remove_one_port(); console callbacks must not take it. */ +static DEFINE_MUTEX(imx_uart_ports_lock); + #if IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE) static void imx_uart_console_putchar(struct uart_port *port, int ch) {
@@ -2455,11 +2459,18 @@ static int imx_uart_probe(struct platform_device *pdev) } } - imx_uart_ports[sport->port.line] = sport; - platform_set_drvdata(pdev, sport); - ret = uart_add_one_port(&imx_uart_uart_driver, &sport->port); + mutex_lock(&imx_uart_ports_lock); + if (imx_uart_ports[sport->port.line]) { + ret = -EBUSY; + } else { + imx_uart_ports[sport->port.line] = sport; + ret = uart_add_one_port(&imx_uart_uart_driver, &sport->port); + if (ret) + imx_uart_ports[sport->port.line] = NULL; + } + mutex_unlock(&imx_uart_ports_lock); err_clk: clk_disable_unprepare(sport->clk_ipg);
@@ -2471,7 +2482,10 @@ static void imx_uart_remove(struct platform_device *pdev) { struct imx_port *sport = platform_get_drvdata(pdev); + mutex_lock(&imx_uart_ports_lock); uart_remove_one_port(&imx_uart_uart_driver, &sport->port); + imx_uart_ports[sport->port.line] = NULL; + mutex_unlock(&imx_uart_ports_lock); } static void imx_uart_restore_context(struct imx_port *sport)
--
2.53.0