From: Bjorn Andersson Date: Thu, 24 Aug 2017 01:04:04 +0000 (-0700) Subject: of/device: Prevent buffer overflow in of_device_modalias() X-Git-Tag: v4.12.12~3 X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3ef5220bdba723f80b0654e58f5a8c05b739d34e;p=linux of/device: Prevent buffer overflow in of_device_modalias() commit 08ab58d9de3eb8498ae0585001d0975e46217a39 upstream. As of_device_get_modalias() returns the number of bytes that would have been written to the target string, regardless of how much did fit in the buffer, it's possible that the returned index points beyond the buffer passed to of_device_modalias() - causing memory beyond the buffer to be null terminated. Fixes: 0634c2958927 ("of: Add function for generating a DT modalias with a newline") Cc: Rob Herring Signed-off-by: Bjorn Andersson Signed-off-by: Rob Herring Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/of/device.c b/drivers/of/device.c index 28c38c756f92..9af44f6dc17b 100644 --- a/drivers/of/device.c +++ b/drivers/of/device.c @@ -274,6 +274,8 @@ ssize_t of_device_modalias(struct device *dev, char *str, ssize_t len) ssize_t sl = of_device_get_modalias(dev, str, len - 2); if (sl < 0) return sl; + if (sl > len - 2) + return -ENOMEM; str[sl++] = '\n'; str[sl] = 0;