rootdev: Fix memory leak

match_sysfs_device allocates a struct dirent that was used with
readdir_r.  When the function was converted to use readdir, the malloc
wasn't removed, so this is now a memory leak.  Remove the malloc
entirely, since readdir returns a pointer to its own memory.

BUG=b:225008839
TEST=FEATURES=test emerge-octopus rootdev

Change-Id: I20325e8b4baebca7ea358ccd804f761aeda2bfa1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/rootdev/+/3804964
Tested-by: Benjamin Gordon <bmgordon@chromium.org>
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
Commit-Queue: Benjamin Gordon <bmgordon@chromium.org>

rootdev.c

diff --git a/rootdev.c b/rootdev.c
index 037140c..eae6212 100644
--- a/rootdev.c
+++ b/rootdev.c
@@ -89,7 +89,7 @@
 
 /* Walks sysfs and recurses into any directory/link that represents
  * a block device to find sub-devices (partitions) for dev.
- * If dev == 0, the name fo the first device in the directory will be returned.
+ * If dev == 0, the name of the first device in the directory will be returned.
  * Returns the device's name in "name" */
 static int match_sysfs_device(char *name, size_t name_len,
                               const char *basedir, dev_t *dev, int depth) {
@@ -133,15 +133,6 @@
     return found;
   }
 
-  /* Allocate a properly sized entry. */
-  entry = malloc(offsetof(struct dirent, d_name) + working_path_size);
-  if (!entry) {
-    warn("malloc(dirent)");
-    free(working_path);
-    closedir(dirp);
-    return found;
-  }
-
   while ((entry = readdir(dirp))) {
     size_t candidate_len = strlen(entry->d_name);
     size_t path_len = 0;