toolchain/58759: makefs: faild to merging with extra-directory using -r option

[hashimoto.kenichi.0615%gmail.com@localhost]

>Number:         58759
>Category:       toolchain
>Synopsis:       makefs: faild to merging with extra-directory using -r option
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Oct 18 11:20:00 +0000 2024
>Originator:     Kenichi Hashimoto
>Release:        NetBSD 9.99.37
>Organization:
Genetec Corporation
>Environment:
NetBSD VM-Hashimoto 9.99.37 NetBSD 9.99.37 (GENERIC) #18: Thu Mar 26 10:59:06 JST 2020  root@VM-Hashimoto:/usr/obj/sys/arch/amd64/compile/GENERIC amd64
>Description:
There is a bug in makefs when using the -r option with the extra-directory merge process.
If a directory contains only one file, merging causes that file to become a 0-byte file.

For example, when creating an installation image and trying to overwrite 
 /var/cron/tabs/root
the operation fails, and the file is reduced to 0 bytes.
>How-To-Repeat:
1. Use makefs with the -r option and specify an extra-directory.
2. Ensure the directory being merged contains only one file.
3. bserve that after merging, the file becomes a 0-byte file instead of retaining its original content.
>Fix:
===================================================================
diff --git a/usr.sbin/makefs/walk.c b/usr.sbin/makefs/walk.c
index 77a75cf4a50d..b83981757755 100644
--- a/usr.sbin/makefs/walk.c
+++ b/usr.sbin/makefs/walk.c
@@ -177,7 +177,16 @@ walk_dir(const char *root, const char *dir, fsnode *parent, fsnode *join,
                                                        continue;
                                                p->next = cur->next;
                                        }
+                                       free(cur->path);
+                                       free(cur->name);
                                        free(cur);
+
+                                       if (prev == cur) {
+                                               cur = join;
+                                               while (cur->next != NULL)
+                                                       cur = cur->next;
+                                               prev = cur;
+                                       }
                                }
                        }
                }
===================================================================