Fix off-by-one in readlink() buffer size handling

readlink() returns the number of bytes in the buffer.

If we do something like

len = readlink(path, buf, sizeof(buf));
buf[len] = '\0';

we might write one byte past the end of the buffer.

Signed-off-by: Thomas Jarosch <thomas.jarosch@intra2net.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/util.c b/util.c
index 50c98c1c..f785f030 100644
--- a/util.c
+++ b/util.c
@@ -1594,7 +1594,7 @@ int start_mdmon(int devnum)
 	if (check_env("MDADM_NO_MDMON"))
 		return 0;
 
-	len = readlink("/proc/self/exe", pathbuf, sizeof(pathbuf));
+	len = readlink("/proc/self/exe", pathbuf, sizeof(pathbuf)-1);
 	if (len > 0) {
 		char *sl;
 		pathbuf[len] = 0;