[PATCH v5 2/3] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Dmitry Antipov]

Go closer to the modern kernel API and use 'strscpy()' and 'kmemdup_nul()'
over an ad-hoc ensure-to-have-'\0' quirks where appropriate.

Signed-off-by: Dmitry Antipov <dmantipov at yandex.ru>
---
v5: switch to fname_len() + 1 to specify strscpy() target buffer size
v4: once again to not forget a filesystem-native (little) to CPU endian swap
v3: fix strscpy() usage as noticed by Zhihao
v2: initial version to join the series
---
 fs/ubifs/journal.c | 18 ++++++------------
 fs/ubifs/replay.c  |  3 +--
 fs/ubifs/super.c   |  8 ++------
 3 files changed, 9 insertions(+), 20 deletions(-)

diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index 40a95a2fad50..8d7f0843d353 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -729,8 +729,7 @@ int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
 	dent->inum = deletion ? 0 : cpu_to_le64(inode->i_ino);
 	dent->type = get_dent_type(inode->i_mode);
 	dent->nlen = cpu_to_le16(fname_len(nm));
-	memcpy(dent->name, fname_name(nm), fname_len(nm));
-	dent->name[fname_len(nm)] = '\0';
+	strscpy(dent->name, fname_name(nm), fname_len(nm) + 1);
 	set_dent_cookie(c, dent);
 
 	zero_dent_node_unused(dent);
@@ -1232,8 +1231,7 @@ int ubifs_jnl_xrename(struct ubifs_info *c, const struct inode *fst_dir,
 	dent1->inum = cpu_to_le64(fst_inode->i_ino);
 	dent1->type = get_dent_type(fst_inode->i_mode);
 	dent1->nlen = cpu_to_le16(fname_len(snd_nm));
-	memcpy(dent1->name, fname_name(snd_nm), fname_len(snd_nm));
-	dent1->name[fname_len(snd_nm)] = '\0';
+	strscpy(dent1->name, fname_name(snd_nm), fname_len(snd_nm) + 1);
 	set_dent_cookie(c, dent1);
 	zero_dent_node_unused(dent1);
 	ubifs_prep_grp_node(c, dent1, dlen1, 0);
@@ -1248,8 +1246,7 @@ int ubifs_jnl_xrename(struct ubifs_info *c, const struct inode *fst_dir,
 	dent2->inum = cpu_to_le64(snd_inode->i_ino);
 	dent2->type = get_dent_type(snd_inode->i_mode);
 	dent2->nlen = cpu_to_le16(fname_len(fst_nm));
-	memcpy(dent2->name, fname_name(fst_nm), fname_len(fst_nm));
-	dent2->name[fname_len(fst_nm)] = '\0';
+	strscpy(dent2->name, fname_name(fst_nm), fname_len(fst_nm) + 1);
 	set_dent_cookie(c, dent2);
 	zero_dent_node_unused(dent2);
 	ubifs_prep_grp_node(c, dent2, dlen2, 0);
@@ -1424,8 +1421,7 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 	dent->inum = cpu_to_le64(old_inode->i_ino);
 	dent->type = get_dent_type(old_inode->i_mode);
 	dent->nlen = cpu_to_le16(fname_len(new_nm));
-	memcpy(dent->name, fname_name(new_nm), fname_len(new_nm));
-	dent->name[fname_len(new_nm)] = '\0';
+	strscpy(dent->name, fname_name(new_nm), fname_len(new_nm) + 1);
 	set_dent_cookie(c, dent);
 	zero_dent_node_unused(dent);
 	ubifs_prep_grp_node(c, dent, dlen1, 0);
@@ -1446,8 +1442,7 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 		dent2->type = DT_UNKNOWN;
 	}
 	dent2->nlen = cpu_to_le16(fname_len(old_nm));
-	memcpy(dent2->name, fname_name(old_nm), fname_len(old_nm));
-	dent2->name[fname_len(old_nm)] = '\0';
+	strscpy(dent2->name, fname_name(old_nm), fname_len(old_nm) + 1);
 	set_dent_cookie(c, dent2);
 	zero_dent_node_unused(dent2);
 	ubifs_prep_grp_node(c, dent2, dlen2, 0);
@@ -1897,8 +1892,7 @@ int ubifs_jnl_delete_xattr(struct ubifs_info *c, const struct inode *host,
 	xent->inum = 0;
 	xent->type = get_dent_type(inode->i_mode);
 	xent->nlen = cpu_to_le16(fname_len(nm));
-	memcpy(xent->name, fname_name(nm), fname_len(nm));
-	xent->name[fname_len(nm)] = '\0';
+	strscpy(xent->name, fname_name(nm), fname_len(nm) + 1);
 	zero_dent_node_unused(xent);
 	ubifs_prep_grp_node(c, xent, xlen, 0);
 
diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index a9a568f4a868..ef6ae63792d1 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -463,8 +463,7 @@ static int insert_dent(struct ubifs_info *c, int lnum, int offs, int len,
 	r->sqnum = sqnum;
 	key_copy(c, key, &r->key);
 	fname_len(&r->nm) = nlen;
-	memcpy(nbuf, name, nlen);
-	nbuf[nlen] = '\0';
+	strscpy(nbuf, name, nlen + 1);
 	fname_name(&r->nm) = nbuf;
 
 	list_add_tail(&r->list, &c->replay_list);
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 9a77d8b64ffa..048c21271db1 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -168,13 +168,11 @@ struct inode *ubifs_iget(struct super_block *sb, unsigned long inum)
 		inode->i_op = &ubifs_file_inode_operations;
 		inode->i_fop = &ubifs_file_operations;
 		if (ui->xattr) {
-			ui->data = kmalloc(ui->data_len + 1, GFP_NOFS);
+			ui->data = kmemdup_nul(ino->data, ui->data_len, GFP_NOFS);
 			if (!ui->data) {
 				err = -ENOMEM;
 				goto out_ino;
 			}
-			memcpy(ui->data, ino->data, ui->data_len);
-			((char *)ui->data)[ui->data_len] = '\0';
 		} else if (ui->data_len != 0) {
 			err = 10;
 			goto out_invalid;
@@ -194,13 +192,11 @@ struct inode *ubifs_iget(struct super_block *sb, unsigned long inum)
 			err = 12;
 			goto out_invalid;
 		}
-		ui->data = kmalloc(ui->data_len + 1, GFP_NOFS);
+		ui->data = kmemdup_nul(ino->data, ui->data_len, GFP_NOFS);
 		if (!ui->data) {
 			err = -ENOMEM;
 			goto out_ino;
 		}
-		memcpy(ui->data, ino->data, ui->data_len);
-		((char *)ui->data)[ui->data_len] = '\0';
 		break;
 	case S_IFBLK:
 	case S_IFCHR:
-- 
2.53.0