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Commit ee096f0d authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Greg Kroah-Hartman
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leds: trigger: netdev: use memcpy in device_name_store 



[ Upstream commit 909346433064b8d840dc82af26161926b8d37558 ]

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.

Fixes: 06f502f5 ("leds: trigger: Introduce a NETDEV trigger")
Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Signed-off-by: default avatarJacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: default avatarSasha Levin (Microsoft) <sashal@kernel.org>
parent 2663959a

drivers/leds/trigger/ledtrig-netdev.c

+2 −1
Original line number Diff line number Diff line
@@ -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;