releases/6.0.19/btrfs-replace-strncpy-with-strscpy.patch

From 26cb43d4c78cba0d04d7f94fbc1d23e7c999d340 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Wed, 4 Jan 2023 11:14:45 -0500
Subject: btrfs: replace strncpy() with strscpy()

[ Upstream commit 63d5429f68a3d4c4aa27e65a05196c17f86c41d6 ]

Using strncpy() on NUL-terminated strings are deprecated.  To avoid
possible forming of non-terminated string strscpy() should be used.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Artem Chernyshev <artem.chernyshev@red-soft.ru>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/ioctl.c      | 9 +++------
 fs/btrfs/rcu-string.h | 6 +++++-
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4fff0067bd2a..c498d5e164eb 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3750,13 +3750,10 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
 	di_args->bytes_used = btrfs_device_get_bytes_used(dev);
 	di_args->total_bytes = btrfs_device_get_total_bytes(dev);
 	memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
-	if (dev->name) {
-		strncpy(di_args->path, rcu_str_deref(dev->name),
-				sizeof(di_args->path) - 1);
-		di_args->path[sizeof(di_args->path) - 1] = 0;
-	} else {
+	if (dev->name)
+		strscpy(di_args->path, rcu_str_deref(dev->name), sizeof(di_args->path));
+	else
 		di_args->path[0] = '\0';
-	}
 
 out:
 	rcu_read_unlock();
diff --git a/fs/btrfs/rcu-string.h b/fs/btrfs/rcu-string.h
index 5c1a617eb25d..5c2b66d155ef 100644
--- a/fs/btrfs/rcu-string.h
+++ b/fs/btrfs/rcu-string.h
@@ -18,7 +18,11 @@ static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t mask)
 					 (len * sizeof(char)), mask);
 	if (!ret)
 		return ret;
-	strncpy(ret->str, src, len);
+	/* Warn if the source got unexpectedly truncated. */
+	if (WARN_ON(strscpy(ret->str, src, len) < 0)) {
+		kfree(ret);
+		return NULL;
+	}
 	return ret;
 }
 
-- 
2.35.1