[PATCH] ubifs: prefer kstrtobool_from_user() over custom helper

[PATCH] ubifs: prefer kstrtobool_from_user() over custom helper

[Dmitry Antipov]

Adjust 'dfs_file_write()' and 'dfs_global_file_write()' to prefer generic
'kstrtobool_from_user()' over an ad-hoc 'interpret_user_input()' helper,
thus making the latter not needed anymore.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
 fs/ubifs/debug.c | 44 ++++++++++----------------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 160c16aa7b6e..252cf82012cf 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2732,39 +2732,14 @@ static ssize_t dfs_file_read(struct file *file, char __user *u, size_t count,
 	return provide_user_output(val, u, count, ppos);
 }
 
-/**
- * interpret_user_input - interpret user debugfs file input.
- * @u: user-provided buffer with the input
- * @count: buffer size
- *
- * This is a helper function which interpret user input to a boolean UBIFS
- * debugfs file. Returns %0 or %1 in case of success and a negative error code
- * in case of failure.
- */
-static int interpret_user_input(const char __user *u, size_t count)
-{
-	size_t buf_size;
-	char buf[8];
-
-	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
-	if (copy_from_user(buf, u, buf_size))
-		return -EFAULT;
-
-	if (buf[0] == '1')
-		return 1;
-	else if (buf[0] == '0')
-		return 0;
-
-	return -EINVAL;
-}
-
 static ssize_t dfs_file_write(struct file *file, const char __user *u,
 			      size_t count, loff_t *ppos)
 {
 	struct ubifs_info *c = file->private_data;
 	struct ubifs_debug_info *d = c->dbg;
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
 	if (file->f_path.dentry == d->dfs_dump_lprops) {
 		ubifs_dump_lprops(c);
@@ -2781,9 +2756,9 @@ static ssize_t dfs_file_write(struct file *file, const char __user *u,
 		return count;
 	}
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == d->dfs_chk_gen)
 		d->chk_gen = val;
@@ -2926,11 +2901,12 @@ static ssize_t dfs_global_file_write(struct file *file, const char __user *u,
 				     size_t count, loff_t *ppos)
 {
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == dfs_chk_gen)
 		ubifs_dbg.chk_gen = val;
-- 
2.53.0


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Re: [PATCH] ubifs: prefer kstrtobool_from_user() over custom helper

[Zhihao Cheng]

在 2026/4/2 16:13, Dmitry Antipov 写道:
> Adjust 'dfs_file_write()' and 'dfs_global_file_write()' to prefer generic
> 'kstrtobool_from_user()' over an ad-hoc 'interpret_user_input()' helper,
> thus making the latter not needed anymore.
> 
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> ---
>   fs/ubifs/debug.c | 44 ++++++++++----------------------------------
>   1 file changed, 10 insertions(+), 34 deletions(-)
> 

Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
> diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
> index 160c16aa7b6e..252cf82012cf 100644
> --- a/fs/ubifs/debug.c
> +++ b/fs/ubifs/debug.c
> @@ -2732,39 +2732,14 @@ static ssize_t dfs_file_read(struct file *file, char __user *u, size_t count,
>   	return provide_user_output(val, u, count, ppos);
>   }
>   
> -/**
> - * interpret_user_input - interpret user debugfs file input.
> - * @u: user-provided buffer with the input
> - * @count: buffer size
> - *
> - * This is a helper function which interpret user input to a boolean UBIFS
> - * debugfs file. Returns %0 or %1 in case of success and a negative error code
> - * in case of failure.
> - */
> -static int interpret_user_input(const char __user *u, size_t count)
> -{
> -	size_t buf_size;
> -	char buf[8];
> -
> -	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
> -	if (copy_from_user(buf, u, buf_size))
> -		return -EFAULT;
> -
> -	if (buf[0] == '1')
> -		return 1;
> -	else if (buf[0] == '0')
> -		return 0;
> -
> -	return -EINVAL;
> -}
> -
>   static ssize_t dfs_file_write(struct file *file, const char __user *u,
>   			      size_t count, loff_t *ppos)
>   {
>   	struct ubifs_info *c = file->private_data;
>   	struct ubifs_debug_info *d = c->dbg;
>   	struct dentry *dent = file->f_path.dentry;
> -	int val;
> +	bool val;
> +	int ret;
>   
>   	if (file->f_path.dentry == d->dfs_dump_lprops) {
>   		ubifs_dump_lprops(c);
> @@ -2781,9 +2756,9 @@ static ssize_t dfs_file_write(struct file *file, const char __user *u,
>   		return count;
>   	}
>   
> -	val = interpret_user_input(u, count);
> -	if (val < 0)
> -		return val;
> +	ret = kstrtobool_from_user(u, count, &val);
> +	if (unlikely(ret))
> +		return ret;
>   
>   	if (dent == d->dfs_chk_gen)
>   		d->chk_gen = val;
> @@ -2926,11 +2901,12 @@ static ssize_t dfs_global_file_write(struct file *file, const char __user *u,
>   				     size_t count, loff_t *ppos)
>   {
>   	struct dentry *dent = file->f_path.dentry;
> -	int val;
> +	bool val;
> +	int ret;
>   
> -	val = interpret_user_input(u, count);
> -	if (val < 0)
> -		return val;
> +	ret = kstrtobool_from_user(u, count, &val);
> +	if (unlikely(ret))
> +		return ret;
>   
>   	if (dent == dfs_chk_gen)
>   		ubifs_dbg.chk_gen = val;
> 


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[PATCH v2 1/2] ubifs: prefer kstrtobool_from_user() over custom helper

[Dmitry Antipov]

Adjust 'dfs_file_write()' and 'dfs_global_file_write()' to prefer generic
'kstrtobool_from_user()' over an ad-hoc 'interpret_user_input()' helper,
thus making the latter not needed anymore.

Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v2: add Reviewed-by: and bump version to match the series
---
 fs/ubifs/debug.c | 44 ++++++++++----------------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 160c16aa7b6e..252cf82012cf 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2732,39 +2732,14 @@ static ssize_t dfs_file_read(struct file *file, char __user *u, size_t count,
 	return provide_user_output(val, u, count, ppos);
 }
 
-/**
- * interpret_user_input - interpret user debugfs file input.
- * @u: user-provided buffer with the input
- * @count: buffer size
- *
- * This is a helper function which interpret user input to a boolean UBIFS
- * debugfs file. Returns %0 or %1 in case of success and a negative error code
- * in case of failure.
- */
-static int interpret_user_input(const char __user *u, size_t count)
-{
-	size_t buf_size;
-	char buf[8];
-
-	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
-	if (copy_from_user(buf, u, buf_size))
-		return -EFAULT;
-
-	if (buf[0] == '1')
-		return 1;
-	else if (buf[0] == '0')
-		return 0;
-
-	return -EINVAL;
-}
-
 static ssize_t dfs_file_write(struct file *file, const char __user *u,
 			      size_t count, loff_t *ppos)
 {
 	struct ubifs_info *c = file->private_data;
 	struct ubifs_debug_info *d = c->dbg;
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
 	if (file->f_path.dentry == d->dfs_dump_lprops) {
 		ubifs_dump_lprops(c);
@@ -2781,9 +2756,9 @@ static ssize_t dfs_file_write(struct file *file, const char __user *u,
 		return count;
 	}
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == d->dfs_chk_gen)
 		d->chk_gen = val;
@@ -2926,11 +2901,12 @@ static ssize_t dfs_global_file_write(struct file *file, const char __user *u,
 				     size_t count, loff_t *ppos)
 {
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == dfs_chk_gen)
 		ubifs_dbg.chk_gen = val;
-- 
2.53.0


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[PATCH v2 2/2] 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@yandex.ru>
---
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 e28ab4395e5c..fa13e988e8b2 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));
 	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));
 	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));
 	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));
 	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));
 	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));
 	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..cb1c3fafa5c5 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);
 	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 03bf924756ca..da2f1067f054 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


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Re: [PATCH v2 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Zhihao Cheng]

在 2026/4/4 0:37, Dmitry Antipov 写道:
> 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@yandex.ru>
> ---
> 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 e28ab4395e5c..fa13e988e8b2 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));

The 'size' param in strscpy() is the size of dst buf, not the string 
name length.
>   	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));
>   	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));
>   	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));
>   	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));
>   	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));
>   	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..cb1c3fafa5c5 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);
>   	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 03bf924756ca..da2f1067f054 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:
> 


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[PATCH v3 1/2] ubifs: prefer kstrtobool_from_user() over custom helper

[Dmitry Antipov]

Adjust 'dfs_file_write()' and 'dfs_global_file_write()' to prefer generic
'kstrtobool_from_user()' over an ad-hoc 'interpret_user_input()' helper,
thus making the latter not needed anymore.

Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v3: bump version to match the series
v2: add Reviewed-by: and bump version to match the series
---
 fs/ubifs/debug.c | 44 ++++++++++----------------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 160c16aa7b6e..252cf82012cf 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2732,39 +2732,14 @@ static ssize_t dfs_file_read(struct file *file, char __user *u, size_t count,
 	return provide_user_output(val, u, count, ppos);
 }
 
-/**
- * interpret_user_input - interpret user debugfs file input.
- * @u: user-provided buffer with the input
- * @count: buffer size
- *
- * This is a helper function which interpret user input to a boolean UBIFS
- * debugfs file. Returns %0 or %1 in case of success and a negative error code
- * in case of failure.
- */
-static int interpret_user_input(const char __user *u, size_t count)
-{
-	size_t buf_size;
-	char buf[8];
-
-	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
-	if (copy_from_user(buf, u, buf_size))
-		return -EFAULT;
-
-	if (buf[0] == '1')
-		return 1;
-	else if (buf[0] == '0')
-		return 0;
-
-	return -EINVAL;
-}
-
 static ssize_t dfs_file_write(struct file *file, const char __user *u,
 			      size_t count, loff_t *ppos)
 {
 	struct ubifs_info *c = file->private_data;
 	struct ubifs_debug_info *d = c->dbg;
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
 	if (file->f_path.dentry == d->dfs_dump_lprops) {
 		ubifs_dump_lprops(c);
@@ -2781,9 +2756,9 @@ static ssize_t dfs_file_write(struct file *file, const char __user *u,
 		return count;
 	}
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == d->dfs_chk_gen)
 		d->chk_gen = val;
@@ -2926,11 +2901,12 @@ static ssize_t dfs_global_file_write(struct file *file, const char __user *u,
 				     size_t count, loff_t *ppos)
 {
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == dfs_chk_gen)
 		ubifs_dbg.chk_gen = val;
-- 
2.53.0


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[PATCH v3 2/2] 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@yandex.ru>
---
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 e28ab4395e5c..b8c4ab8990c2 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), dent->nlen + 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), dent1->nlen + 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), dent2->nlen + 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), dent->nlen + 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), dent2->nlen + 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), xent->nlen + 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 03bf924756ca..da2f1067f054 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


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Re: [PATCH v3 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Zhihao Cheng]

在 2026/4/8 0:05, Dmitry Antipov 写道:
> 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@yandex.ru>
> ---
> 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 e28ab4395e5c..b8c4ab8990c2 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), dent->nlen + 1);

The 'dent->nlen' is a little endian type, cannot be used directly.
>   	set_dent_cookie(c, dent);
>   
>   	zero_dent_node_unused(dent);



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[PATCH v4 1/2] ubifs: prefer kstrtobool_from_user() over custom helper

[Dmitry Antipov]

Adjust 'dfs_file_write()' and 'dfs_global_file_write()' to prefer generic
'kstrtobool_from_user()' over an ad-hoc 'interpret_user_input()' helper,
thus making the latter not needed anymore.

Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v3 and upwards: bump version to match the series
v2: add Reviewed-by: and bump version to match the series
---
 fs/ubifs/debug.c | 44 ++++++++++----------------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 160c16aa7b6e..252cf82012cf 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2732,39 +2732,14 @@ static ssize_t dfs_file_read(struct file *file, char __user *u, size_t count,
 	return provide_user_output(val, u, count, ppos);
 }
 
-/**
- * interpret_user_input - interpret user debugfs file input.
- * @u: user-provided buffer with the input
- * @count: buffer size
- *
- * This is a helper function which interpret user input to a boolean UBIFS
- * debugfs file. Returns %0 or %1 in case of success and a negative error code
- * in case of failure.
- */
-static int interpret_user_input(const char __user *u, size_t count)
-{
-	size_t buf_size;
-	char buf[8];
-
-	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
-	if (copy_from_user(buf, u, buf_size))
-		return -EFAULT;
-
-	if (buf[0] == '1')
-		return 1;
-	else if (buf[0] == '0')
-		return 0;
-
-	return -EINVAL;
-}
-
 static ssize_t dfs_file_write(struct file *file, const char __user *u,
 			      size_t count, loff_t *ppos)
 {
 	struct ubifs_info *c = file->private_data;
 	struct ubifs_debug_info *d = c->dbg;
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
 	if (file->f_path.dentry == d->dfs_dump_lprops) {
 		ubifs_dump_lprops(c);
@@ -2781,9 +2756,9 @@ static ssize_t dfs_file_write(struct file *file, const char __user *u,
 		return count;
 	}
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == d->dfs_chk_gen)
 		d->chk_gen = val;
@@ -2926,11 +2901,12 @@ static ssize_t dfs_global_file_write(struct file *file, const char __user *u,
 				     size_t count, loff_t *ppos)
 {
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == dfs_chk_gen)
 		ubifs_dbg.chk_gen = val;
-- 
2.53.0


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[PATCH v4 2/2] 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@yandex.ru>
---
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 e28ab4395e5c..43e19c83ad6d 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), le16_to_cpu(dent->nlen) + 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), le16_to_cpu(dent1->nlen) + 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), le16_to_cpu(dent2->nlen) + 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), le16_to_cpu(dent->nlen) + 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), le16_to_cpu(dent2->nlen) + 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), le16_to_cpu(xent->nlen) + 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 03bf924756ca..da2f1067f054 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


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Re: [PATCH v4 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Zhihao Cheng]

在 2026/4/9 12:56, Dmitry Antipov 写道:
> 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@yandex.ru>
> ---
> 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 e28ab4395e5c..43e19c83ad6d 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), le16_to_cpu(dent->nlen) + 1);

I think we can use 'fname_len(nm) + 1' to replace 
'le16_to_cpu(dent->nlen) + 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), le16_to_cpu(dent1->nlen) + 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), le16_to_cpu(dent2->nlen) + 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), le16_to_cpu(dent->nlen) + 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), le16_to_cpu(dent2->nlen) + 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), le16_to_cpu(xent->nlen) + 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 03bf924756ca..da2f1067f054 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:
> 


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Re: [PATCH v4 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Richard Weinberger]

----- Ursprüngliche Mail -----
> Von: "chengzhihao1" <chengzhihao1@huawei.com>
> An: "Dmitry Antipov" <dmantipov@yandex.ru>
> CC: "richard" <richard@nod.at>, "linux-mtd" <linux-mtd@lists.infradead.org>
> Gesendet: Freitag, 10. April 2026 03:06:39
> Betreff: Re: [PATCH v4 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

> 在 2026/4/9 12:56, Dmitry Antipov 写道:
>> 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@yandex.ru>

Dmitry, how are you testing these changes?

Thanks,
//richard

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Re: [PATCH v4 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Dmitry Antipov]

On Fri, 2026-04-10 at 07:57 +0200, Richard Weinberger wrote:

> Dmitry, how are you testing these changes?

Build with:

CONFIG_KASAN=y

CONFIG_MTD_NAND_NANDSIM=m

CONFIG_MTD_UBI=m
CONFIG_MTD_UBI_WL_THRESHOLD=4096
CONFIG_MTD_UBI_BEB_LIMIT=20
CONFIG_UBIFS_FS=m
CONFIG_UBIFS_FS_ADVANCED_COMPR=y
CONFIG_UBIFS_FS_LZO=y
CONFIG_UBIFS_FS_ZLIB=y
CONFIG_UBIFS_FS_ZSTD=y
CONFIG_UBIFS_ATIME_SUPPORT=y
CONFIG_UBIFS_FS_XATTR=y
CONFIG_UBIFS_FS_SECURITY=y
CONFIG_UBIFS_FS_AUTHENTICATION=y

and boot (QEMU VM), then:

# modprobe nandsim second_id_byte=0xdc third_id_byte=0x80 fourth_id_byte=0x1d
[   24.282259] [nandsim] warning: read_byte: unexpected data output cycle, state is STATE_READY return 0x0
[   24.282787] [nandsim] warning: read_byte: unexpected data output cycle, state is STATE_READY return 0x0
[   24.283441] [nandsim] warning: read_byte: unexpected data output cycle, state is STATE_READY return 0x0
[   24.284083] [nandsim] warning: read_byte: unexpected data output cycle, state is STATE_READY return 0x0
[   24.284783] [nandsim] warning: read_byte: unexpected data output cycle, state is STATE_READY return 0x0
[   24.285473] nand: device found, Manufacturer ID: 0x98, Chip ID: 0xdc
[   24.285932] nand: Toshiba NAND 512MiB 3,3V 8-bit
[   24.286275] nand: 512 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64
[   24.286749] flash size: 512 MiB
[   24.286925] page size: 2048 bytes
[   24.287104] OOB area size: 64 bytes
[   24.287337] sector size: 128 KiB
[   24.287578] pages number: 262144
[   24.287817] pages per sector: 64
[   24.288068] bus width: 8
[   24.288269] bits in sector size: 17
[   24.288527] bits in page size: 11
[   24.288775] bits in OOB size: 6
[   24.289024] flash size with OOB: 540672 KiB
[   24.289334] page address bytes: 5
[   24.289572] sector address bytes: 3
[   24.289837] options: 0x8
[   24.290676] Scanning device for bad blocks
[   24.311973] Creating 1 MTD partitions on "NAND 512MiB 3,3V 8-bit":
[   24.312376] 0x000000000000-0x000020000000 : "NAND simulator partition 0"

# modprobe ubi mtd=0
[   44.884572] ubi0: attaching mtd0
[   44.893002] ubi0: scanning is finished
[   44.893308] ubi0: empty MTD device detected
[   44.947667] ubi0: attached mtd0 (name "NAND 512MiB 3,3V 8-bit", size 512 MiB)
[   44.948231] ubi0: PEB size: 131072 bytes (128 KiB), LEB size: 129024 bytes
[   44.948719] ubi0: min./max. I/O unit sizes: 2048/2048, sub-page size 512
[   44.949206] ubi0: VID header offset: 512 (aligned 512), data offset: 2048
[   44.949686] ubi0: good PEBs: 4096, bad PEBs: 0, corrupted PEBs: 0
[   44.950113] ubi0: user volume: 0, internal volumes: 1, max. volumes count: 128
[   44.950639] ubi0: max/mean erase counter: 0/0, WL threshold: 4096, image sequence number: 3902257690
[   44.951285] ubi0: available PEBs: 4012, total reserved PEBs: 84, PEBs reserved for bad PEB handling: 80
[   44.951946] ubi0: background thread "ubi_bgt0d" started, PID 1022

# ubimkvol /dev/ubi0 -N test -m
Set volume size to 517644288
Volume ID 0, size 4012 LEBs (517644288 bytes, 493.6 MiB), LEB size 129024 bytes (126.0 KiB), dynamic, name "test", alignment 1

# mount -t ubifs ubi0:test /mnt/ubifs
[  122.812026] UBIFS (ubi0:0): default file-system created
[  122.812377] UBIFS (ubi0:0): Mounting in unauthenticated mode
[  122.813415] UBIFS (ubi0:0): background thread "ubifs_bgt0_0" started, PID 1053
[  122.813963] UBIFS (ubi0:0): UBIFS: mounted UBI device 0, volume 0, name "test"
[  122.814334] UBIFS (ubi0:0): LEB size: 129024 bytes (126 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[  122.814849] UBIFS (ubi0:0): FS size: 515579904 bytes (491 MiB, 3996 LEBs), max 4012 LEBs, journal size 25804800 bytes (24 MiB, 200 LEBs)
[  122.815701] UBIFS (ubi0:0): reserved for root: 4952683 bytes (4836 KiB)
[  122.816225] UBIFS (ubi0:0): media format: w5/r0 (latest is w5/r0), UUID 999464F1-4417-4523-B773-57C6EBD728DC, small LPT model
[  122.817041] UBIFS (ubi0:0): full atime support is enabled.

# cp -a [~390M source tree] /mnt/ubifs
# diff -ur [tree] /mnt/ubifs/[copy of that tree] ; no output hopefully means OK

# umount /mnt/ubifs
[  179.322533] UBIFS (ubi0:0): un-mount UBI device 0
[  179.323801] UBIFS (ubi0:0): background thread "ubifs_bgt0_0" stops

# mount -t ubifs ubi0:test /mnt/ubifs
[  185.313439] UBIFS (ubi0:0): Mounting in unauthenticated mode
...

# diff -ur [tree] /mnt/ubifs/[copy of that tree] ; likewise

etc.

Dmitry

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Re: [PATCH v4 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Dmitry Antipov]

On Fri, 2026-04-10 at 07:57 +0200, Richard Weinberger wrote:

> Dmitry, how are you testing these changes?

Build with:

CONFIG_KASAN=y

CONFIG_MTD_NAND_NANDSIM=m

CONFIG_MTD_UBI=m
CONFIG_MTD_UBI_WL_THRESHOLD=4096
CONFIG_MTD_UBI_BEB_LIMIT=20
CONFIG_UBIFS_FS=m
CONFIG_UBIFS_FS_ADVANCED_COMPR=y
CONFIG_UBIFS_FS_LZO=y
CONFIG_UBIFS_FS_ZLIB=y
CONFIG_UBIFS_FS_ZSTD=y
CONFIG_UBIFS_ATIME_SUPPORT=y
CONFIG_UBIFS_FS_XATTR=y
CONFIG_UBIFS_FS_SECURITY=y
CONFIG_UBIFS_FS_AUTHENTICATION=y

and boot (QEMU VM). Then use nandsim to create ~512M ubifs volume:

# modprobe nandsim second_id_byte=0xdc third_id_byte=0x80 fourth_id_byte=0x1d
# modprobe ubi mtd=0
# ubimkvol /dev/ubi0 -N test -m
Set volume size to 517644288
Volume ID 0, size 4012 LEBs (517644288 bytes, 493.6 MiB), LEB size 129024 bytes (126.0 KiB), dynamic, name "test", alignment 1
# mount -t ubifs ubi0:test /mnt/ubifs

And do basic consistency check with something like:

# cp -a [~390M source tree] /mnt/ubifs
# diff -ur [tree] /mnt/ubifs/[copy of that tree] ; no output hopefully means OK
# umount /mnt/ubifs
# mount -t ubifs ubi0:test /mnt/ubifs
# diff -ur [tree] /mnt/ubifs/[copy of that tree] ; likewise

etc.

Dmitry

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Re: [PATCH v4 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Dmitry Antipov]

On Fri, 2026-04-10 at 07:57 +0200, Richard Weinberger wrote:

> Dmitry, how are you testing these changes?

# modprobe nandsim second_id_byte=0xdc third_id_byte=0x80 fourth_id_byte=0x1d
# modprobe ubi mtd=0
# ubimkvol /dev/ubi0 -N test -m
Set volume size to 517644288
Volume ID 0, size 4012 LEBs (517644288 bytes, 493.6 MiB), LEB size 129024
bytes (126.0 KiB), dynamic, name "test", alignment 1
# mount -t ubifs ubi0:test /mnt/ubifs
# cp -a [~390M source tree] /mnt/ubifs
# diff -ur [tree] /mnt/ubifs/[tree]
# umount /mnt/ubifs
# sync
# mount /mnt/ubifs
# diff -ur [tree] /mnt/ubifs/[tree]

etc, etc. And yes, I'm aware of fsck.ubifs since 2.3.0 of mtd-utils.

Dmitry

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Re: [PATCH v4 2/2] ubifs: use strscpy() and kmemdup_nul() where appropriate

[Zhihao Cheng]

在 2026/4/10 20:00, Dmitry Antipov 写道:
> On Fri, 2026-04-10 at 07:57 +0200, Richard Weinberger wrote:
> 
>> Dmitry, how are you testing these changes?
> 
> Build with:
> 
> CONFIG_KASAN=y

Hi, Dmitry
I'm pleasure with CONFIG_KASAN=y, and a fsstress test(>8h) for ubifs is 
still needed.
> 
> CONFIG_MTD_NAND_NANDSIM=m
> 
> CONFIG_MTD_UBI=m
> CONFIG_MTD_UBI_WL_THRESHOLD=4096
> CONFIG_MTD_UBI_BEB_LIMIT=20
> CONFIG_UBIFS_FS=m
> CONFIG_UBIFS_FS_ADVANCED_COMPR=y
> CONFIG_UBIFS_FS_LZO=y
> CONFIG_UBIFS_FS_ZLIB=y
> CONFIG_UBIFS_FS_ZSTD=y
> CONFIG_UBIFS_ATIME_SUPPORT=y
> CONFIG_UBIFS_FS_XATTR=y
> CONFIG_UBIFS_FS_SECURITY=y
> CONFIG_UBIFS_FS_AUTHENTICATION=y
> 
> and boot (QEMU VM). Then use nandsim to create ~512M ubifs volume:
> 
> # modprobe nandsim second_id_byte=0xdc third_id_byte=0x80 fourth_id_byte=0x1d
> # modprobe ubi mtd=0
> # ubimkvol /dev/ubi0 -N test -m
> Set volume size to 517644288
> Volume ID 0, size 4012 LEBs (517644288 bytes, 493.6 MiB), LEB size 129024 bytes (126.0 KiB), dynamic, name "test", alignment 1
> # mount -t ubifs ubi0:test /mnt/ubifs
> 
> And do basic consistency check with something like:
> 
> # cp -a [~390M source tree] /mnt/ubifs
> # diff -ur [tree] /mnt/ubifs/[copy of that tree] ; no output hopefully means OK
> # umount /mnt/ubifs
> # mount -t ubifs ubi0:test /mnt/ubifs
> # diff -ur [tree] /mnt/ubifs/[copy of that tree] ; likewise
> 
> etc.
> 
> Dmitry
> .
> 


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