From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Date: Wed, 6 Apr 2022 18:17:43 +0530
Subject: [PATCH] fs/f2fs: Do not copy file names that are too long

A corrupt f2fs file system might specify a name length which is greater
than the maximum name length supported by the GRUB f2fs driver.

We will allocate enough memory to store the overly long name, but there
are only F2FS_NAME_LEN bytes in the source, so we would read past the end
of the source.

While checking directory entries, do not copy a file name with an invalid
length.

Signed-off-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit 9a891f638509e031d322c94e3cbcf38d36f3993a)
---
 grub-core/fs/f2fs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/grub-core/fs/f2fs.c b/grub-core/fs/f2fs.c
index 8898b235e0..df6beb544c 100644
--- a/grub-core/fs/f2fs.c
+++ b/grub-core/fs/f2fs.c
@@ -1003,6 +1003,10 @@ grub_f2fs_check_dentries (struct grub_f2fs_dir_iter_ctx *ctx)
 
       ftype = ctx->dentry[i].file_type;
       name_len = grub_le_to_cpu16 (ctx->dentry[i].name_len);
+
+      if (name_len >= F2FS_NAME_LEN)
+        return 0;
+
       filename = grub_malloc (name_len + 1);
       if (!filename)
         return 0;