initramfs: make dir_entry.name a flexible array member

dir_entry.name is currently allocated via a separate kstrdup().  Change it
to a flexible array member and allocate it along with struct dir_entry.

Link: https://lkml.kernel.org/r/20220404093429.27570-3-ddiss@suse.de
Signed-off-by: David Disseldorp <ddiss@suse.de>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Martin Wilck <mwilck@suse.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/init/initramfs.c b/init/initramfs.c
index 2f79b3ec0b40b0e7af3c69919cc9b93c3aec4a10..656d2d71349fd36624f7de9d241b294714eac61e 100644 (file)
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -130,17 +130,20 @@ static long __init do_utime(char *filename, time64_t mtime)
 static __initdata LIST_HEAD(dir_list);
 struct dir_entry {
        struct list_head list;
-       char *name;
        time64_t mtime;
+       char name[];
 };
 
 static void __init dir_add(const char *name, time64_t mtime)
 {
-       struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
+       size_t nlen = strlen(name) + 1;
+       struct dir_entry *de;
+
+       de = kmalloc(sizeof(struct dir_entry) + nlen, GFP_KERNEL);
        if (!de)
                panic_show_mem("can't allocate dir_entry buffer");
        INIT_LIST_HEAD(&de->list);
-       de->name = kstrdup(name, GFP_KERNEL);
+       strscpy(de->name, name, nlen);
        de->mtime = mtime;
        list_add(&de->list, &dir_list);
 }
@@ -151,7 +154,6 @@ static void __init dir_utime(void)
        list_for_each_entry_safe(de, tmp, &dir_list, list) {
                list_del(&de->list);
                do_utime(de->name, de->mtime);
-               kfree(de->name);
                kfree(de);
        }
 }