From 179a5bc4b8cbe68ca675057b960dd805867e41c4 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Tue, 27 Jan 2015 16:00:19 +0300 Subject: [PATCH] net/9p: use memcpy() instead of snprintf() in p9_mount_tag_show() p9_mount_tag_show() uses '%s' format string to print non-NULL terminated chan->tag string. This leads to out of bounds memory read, because format '%s' implies that string is NULL-terminated. The length of string is know here, so its simpler and safer to use memcpy instead of snprintf(). Signed-off-by: Andrey Ryabinin Signed-off-by: Dominique Martinet Signed-off-by: Eric Van Hensbergen --- net/9p/trans_virtio.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 36a1a739ad68..486df019f875 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -504,7 +504,10 @@ static ssize_t p9_mount_tag_show(struct device *dev, vdev = dev_to_virtio(dev); chan = vdev->priv; - return snprintf(buf, chan->tag_len + 1, "%s", chan->tag); + memcpy(buf, chan->tag, chan->tag_len); + buf[chan->tag_len] = 0; + + return chan->tag_len + 1; } static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); -- 2.20.1