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/policy.c b/policy.c
index ef483537..7959c970 100644
--- a/policy.c
+++ b/policy.c
@@ -222,7 +222,7 @@ static char *disk_path(struct mdinfo *disk)
 	closedir(by_path);
 	/* A NULL path isn't really acceptable - use the devname.. */
 	sprintf(symlink, "/sys/dev/block/%d:%d", disk->disk.major, disk->disk.minor);
-	rv = readlink(symlink, nm, sizeof(nm));
+	rv = readlink(symlink, nm, sizeof(nm)-1);
 	if (rv > 0) {
 		char *dname;
 		nm[rv] = 0;