From: Rasmus Villemoes linux@rasmusvillemoes.dk
[ 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: 06f502f57d0d ("leds: trigger: Introduce a NETDEV trigger") Signed-off-by: Rasmus Villemoes linux@rasmusvillemoes.dk Acked-by: Pavel Machek pavel@ucw.cz Signed-off-by: Jacek Anaszewski jacek.anaszewski@gmail.com Signed-off-by: Sasha Levin (Microsoft) sashal@kernel.org --- 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 167a94c02d05..136f86a1627d 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;