Messages in this thread Patch in this message | | | From | Rasmus Villemoes <> | Subject | [PATCH v2 1/6] leds: netdev trigger: use memcpy in device_name_store | Date | Thu, 14 Mar 2019 15:06:14 +0100 |
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If userspace doesn't end the input with a newline (which can easily happen if the write happens from a C program that does write(fd, iface, strlen(iface))), we may end up including garbage from a previous, longer value in the device_name. For example
# cat device_name
# printf 'eth12' > device_name # cat device_name eth12 # printf 'eth3' > device_name # cat device_name eth32
I highly doubt anybody is relying on this behaviour, so switch to simply copying the bytes (we've already checked that size is < IFNAMSIZ) and unconditionally zero-terminate it; of course, we also still have to strip a trailing newline.
This is also preparation for future patches.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> --- drivers/leds/trigger/ledtrig-netdev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/leds/trigger/ledtrig-netdev.c b/drivers/leds/trigger/ledtrig-netdev.c index 3dd3ed46d473..8d476b92f58c 100644 --- a/drivers/leds/trigger/ledtrig-netdev.c +++ b/drivers/leds/trigger/ledtrig-netdev.c @@ -122,7 +122,8 @@ static ssize_t device_name_store(struct device *dev, trigger_data->net_dev = NULL; } - strncpy(trigger_data->device_name, buf, size); + memcpy(trigger_data->device_name, buf, size); + trigger_data->device_name[size] = 0; if (size > 0 && trigger_data->device_name[size - 1] == '\n') trigger_data->device_name[size - 1] = 0; -- 2.20.1
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