linux-hardening - [PATCH 2/3] ext4: use memcpy() instead of strcpy()

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Message-ID: <20250712181249.434530-2-tytso@mit.edu>
Date: Sat, 12 Jul 2025 14:12:48 -0400
From: "Theodore Ts'o" <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: linux-hardening@...r.kernel.org, ethan@...ancedwards.com,
        "Theodore Ts'o" <tytso@....edu>
Subject: [PATCH 2/3] ext4: use memcpy() instead of strcpy()

The strcpy() function is considered dangerous and eeeevil by people
who are using sophisticated code analysis tools such as "grep".  This
is true even when a quick inspection would show that the source is a
constant string ("." or "..") and the destination is a fixed array
which is guaranteed to have enough space.  Make the "grep" code
analysis tool happy by using memcpy() isstead of strcpy().  :-)

Signed-off-by: Theodore Ts'o <tytso@....edu>
---
 fs/ext4/inline.c | 4 ++--
 fs/ext4/namei.c  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index a1bbcdf40824..eeee007251e0 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1315,7 +1315,7 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 		if (pos == 0) {
 			fake.inode = cpu_to_le32(inode->i_ino);
 			fake.name_len = 1;
-			strcpy(fake.name, ".");
+			memcpy(fake.name, ".", 2);
 			fake.rec_len = ext4_rec_len_to_disk(
 					  ext4_dir_rec_len(fake.name_len, NULL),
 					  inline_size);
@@ -1325,7 +1325,7 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 		} else if (pos == EXT4_INLINE_DOTDOT_OFFSET) {
 			fake.inode = cpu_to_le32(parent_ino);
 			fake.name_len = 2;
-			strcpy(fake.name, "..");
+			memcpy(fake.name, "..", 3);
 			fake.rec_len = ext4_rec_len_to_disk(
 					  ext4_dir_rec_len(fake.name_len, NULL),
 					  inline_size);
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index b82f5841c65a..9913a94b6a6d 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2924,7 +2924,7 @@ struct ext4_dir_entry_2 *ext4_init_dot_dotdot(struct inode *inode,
 	de->name_len = 1;
 	de->rec_len = ext4_rec_len_to_disk(ext4_dir_rec_len(de->name_len, NULL),
 					   blocksize);
-	strcpy(de->name, ".");
+	memcpy(de->name, ".", 2);
 	ext4_set_de_type(inode->i_sb, de, S_IFDIR);
 
 	de = ext4_next_entry(de, blocksize);
@@ -2938,7 +2938,7 @@ struct ext4_dir_entry_2 *ext4_init_dot_dotdot(struct inode *inode,
 		de->rec_len = ext4_rec_len_to_disk(
 					ext4_dir_rec_len(de->name_len, NULL),
 					blocksize);
-	strcpy(de->name, "..");
+	memcpy(de->name, "..", 3);
 	ext4_set_de_type(inode->i_sb, de, S_IFDIR);
 
 	return ext4_next_entry(de, blocksize);
-- 
2.47.2