Commit 2e41f274 authored by Akinobu Mita's avatar Akinobu Mita Committed by Andrew Morton
Browse files

libfs: add DEFINE_SIMPLE_ATTRIBUTE_SIGNED for signed value 

Patch series "fix error when writing negative value to simple attribute
files".

The simple attribute files do not accept a negative value since the commit
488dac0c ("libfs: fix error cast of negative value in
simple_attr_write()"), but some attribute files want to accept a negative
value.


This patch (of 3):

The simple attribute files do not accept a negative value since the commit
488dac0c ("libfs: fix error cast of negative value in
simple_attr_write()"), so we have to use a 64-bit value to write a
negative value.

This adds DEFINE_SIMPLE_ATTRIBUTE_SIGNED for a signed value.

Link: https://lkml.kernel.org/r/20220919172418.45257-1-akinobu.mita@gmail.com
Link: https://lkml.kernel.org/r/20220919172418.45257-2-akinobu.mita@gmail.com


Fixes: 488dac0c ("libfs: fix error cast of negative value in simple_attr_write()")
Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Reported-by: default avatarZhao Gongyi <zhaogongyi@huawei.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Wei Yongjun <weiyongjun1@huawei.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7b9cbc77

fs/libfs.c

+19 −3
Original line number Diff line number Diff line
@@ -995,8 +995,8 @@ ssize_t simple_attr_read(struct file *file, char __user *buf, 
EXPORT_SYMBOL_GPL(simple_attr_read);



/* interpret the buffer as a number to call the set function with */

ssize_t simple_attr_write(struct file *file, const char __user *buf,

			  size_t len, loff_t *ppos)

static ssize_t simple_attr_write_xsigned(struct file *file, const char __user *buf,

			  size_t len, loff_t *ppos, bool is_signed)

{

	struct simple_attr *attr;

	unsigned long long val;
@@ -1017,6 +1017,9 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf, 
		goto out;



	attr->set_buf[size] = '\0';

	if (is_signed)

		ret = kstrtoll(attr->set_buf, 0, &val);

	else

		ret = kstrtoull(attr->set_buf, 0, &val);

	if (ret)

		goto out;
@@ -1027,8 +1030,21 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf, 
	mutex_unlock(&attr->mutex);

	return ret;

}



ssize_t simple_attr_write(struct file *file, const char __user *buf,

			  size_t len, loff_t *ppos)

{

	return simple_attr_write_xsigned(file, buf, len, ppos, false);

}

EXPORT_SYMBOL_GPL(simple_attr_write);



ssize_t simple_attr_write_signed(struct file *file, const char __user *buf,

			  size_t len, loff_t *ppos)

{

	return simple_attr_write_xsigned(file, buf, len, ppos, true);

}

EXPORT_SYMBOL_GPL(simple_attr_write_signed);



/**

 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation

 * @sb:		filesystem to do the file handle conversion on

include/linux/fs.h

+10 −2
Original line number Diff line number Diff line
@@ -3485,7 +3485,7 @@ void simple_transaction_set(struct file *file, size_t n); 
 * All attributes contain a text representation of a numeric value

 * that are accessed with the get() and set() functions.

 */

#define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)		\

#define DEFINE_SIMPLE_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, __is_signed)	\

static int __fops ## _open(struct inode *inode, struct file *file)	\

{									\

	__simple_attr_check_format(__fmt, 0ull);			\
@@ -3496,10 +3496,16 @@ static const struct file_operations __fops = { \ 
	.open	 = __fops ## _open,					\

	.release = simple_attr_release,					\

	.read	 = simple_attr_read,					\

	.write	 = simple_attr_write,					\

	.write	 = (__is_signed) ? simple_attr_write_signed : simple_attr_write,	\

	.llseek	 = generic_file_llseek,					\

}



#define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)		\

	DEFINE_SIMPLE_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, false)



#define DEFINE_SIMPLE_ATTRIBUTE_SIGNED(__fops, __get, __set, __fmt)	\

	DEFINE_SIMPLE_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, true)



static inline __printf(1, 2)

void __simple_attr_check_format(const char *fmt, ...)

{
@@ -3514,6 +3520,8 @@ ssize_t simple_attr_read(struct file *file, char __user *buf, 
			 size_t len, loff_t *ppos);

ssize_t simple_attr_write(struct file *file, const char __user *buf,

			  size_t len, loff_t *ppos);

ssize_t simple_attr_write_signed(struct file *file, const char __user *buf,

				 size_t len, loff_t *ppos);



struct ctl_table;

int __init list_bdev_fs_names(char *buf, size_t size);