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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2019-03-14 15:06:14 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-04 09:20:22 +0200
commitee096f0dc4a44a3d6cae27dce87abeea71b4680f (patch)
treebe2206102110419e2bdbe67c0f3884b9f1b2bfba
parent2663959af22c485a5ee662f8189075912e3280b3 (diff)
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: 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>
-rw-r--r--drivers/leds/trigger/ledtrig-netdev.c3
1 files changed, 2 insertions, 1 deletions
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;