[PATCH v2 2/2] serial: samsung: Fix possible out of bounds access on non-DT platform

From: Krzysztof Kozlowski
Date: Tue May 31 2016 - 10:00:34 EST

On non-DeviceTree platforms, the index of serial device is a static
variable incremented on each probe. It is incremented even if deferred
probe happens when getting the clock in s3c24xx_serial_init_port().

This index is used for referencing elements of statically allocated
s3c24xx_serial_ports array. In case of re-probe, the index will point
outside of this array leading to memory corruption.

Increment the index only on successful probe.

Reported-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Fixes: b497549a035c ("[ARM] S3C24XX: Split serial driver into core and per-cpu drivers")
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>


Not cc-ing stable because:
1. It is just a possibility, not really reproduced (I don't have non-DT
2. I am not sure whether deferred probe may happen on non-DT platform.

Changes since v1:
1. New patch.
drivers/tty/serial/samsung.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index f0bd2ec0db59..4d2924f61e0b 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1844,8 +1844,6 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
ourport->min_dma_size = max_t(int, ourport->port.fifosize,

- probe_index++;
dbg("%s: initialising port %p...\n", __func__, ourport);

ret = s3c24xx_serial_init_port(ourport, pdev);
@@ -1875,6 +1873,8 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
if (ret < 0)
dev_err(&pdev->dev, "failed to add cpufreq notifier\n");

+ probe_index++;
return 0;