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 <a.ryabi...@samsung.com>
---
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 daa749c..9d64145 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);
--
2.2.2
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