linux-kernel - [PATCH AUTOSEL 6.4 01/16] vfs: Replace all non-returning strlcpy with strscpy

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Message-Id: <20230702193815.1775684-1-sashal@kernel.org>
Date:   Sun,  2 Jul 2023 15:38:00 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Azeem Shaikh <azeemshaikh38@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Christian Brauner <brauner@...nel.org>,
        Sasha Levin <sashal@...nel.org>, viro@...iv.linux.org.uk,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH AUTOSEL 6.4 01/16] vfs: Replace all non-returning strlcpy with strscpy

From: Azeem Shaikh <azeemshaikh38@...il.com>

[ Upstream commit c642256b91770e201519d037a91f255a617a4602 ]

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
Message-Id: <20230510221119.3508930-1-azeemshaikh38@...il.com>
Signed-off-by: Christian Brauner <brauner@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/char_dev.c | 2 +-
 fs/super.c    | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/char_dev.c b/fs/char_dev.c
index 13deb45f1ec65..950b6919fb872 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -150,7 +150,7 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 	cd->major = major;
 	cd->baseminor = baseminor;
 	cd->minorct = minorct;
-	strlcpy(cd->name, name, sizeof(cd->name));
+	strscpy(cd->name, name, sizeof(cd->name));
 
 	if (!prev) {
 		cd->next = curr;
diff --git a/fs/super.c b/fs/super.c
index 04bc62ab7dfea..09668ddfbbd55 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -595,7 +595,7 @@ struct super_block *sget_fc(struct fs_context *fc,
 	fc->s_fs_info = NULL;
 	s->s_type = fc->fs_type;
 	s->s_iflags |= fc->s_iflags;
-	strlcpy(s->s_id, s->s_type->name, sizeof(s->s_id));
+	strscpy(s->s_id, s->s_type->name, sizeof(s->s_id));
 	list_add_tail(&s->s_list, &super_blocks);
 	hlist_add_head(&s->s_instances, &s->s_type->fs_supers);
 	spin_unlock(&sb_lock);
@@ -674,7 +674,7 @@ struct super_block *sget(struct file_system_type *type,
 		return ERR_PTR(err);
 	}
 	s->s_type = type;
-	strlcpy(s->s_id, type->name, sizeof(s->s_id));
+	strscpy(s->s_id, type->name, sizeof(s->s_id));
 	list_add_tail(&s->s_list, &super_blocks);
 	hlist_add_head(&s->s_instances, &type->fs_supers);
 	spin_unlock(&sb_lock);
-- 
2.39.2