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Commit 5c27b46c authored by Akinobu Mita's avatar Akinobu Mita Committed by Greg Kroah-Hartman
Browse files

debugfs: fix error when writing negative value to atomic_t debugfs file 

[ Upstream commit d472cf797c4e268613dbce5ec9b95d0bcae19ecb ]

The simple attribute files do not accept a negative value since the commit
488dac0c9237 ("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 for a debugfs file created by debugfs_create_atomic_t().

This restores the previous behaviour by introducing
DEFINE_DEBUGFS_ATTRIBUTE_SIGNED for a signed value.

Link: https://lkml.kernel.org/r/20220919172418.45257-4-akinobu.mita@gmail.com


Fixes: 488dac0c9237 ("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>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent c7bd4927

Documentation/fault-injection/fault-injection.rst

+4 −6
Original line number Diff line number Diff line
@@ -75,9 +75,7 @@ configuration of fault-injection capabilities. 
- /sys/kernel/debug/fail*/times:



	specifies how many times failures may happen at most. A value of -1

	means "no limit". Note, though, that this file only accepts unsigned

	values. So, if you want to specify -1, you better use 'printf' instead

	of 'echo', e.g.: $ printf %#x -1 > times

	means "no limit".



- /sys/kernel/debug/fail*/space:
@@ -254,7 +252,7 @@ Application Examples 
    echo Y > /sys/kernel/debug/$FAILTYPE/task-filter

    echo 10 > /sys/kernel/debug/$FAILTYPE/probability

    echo 100 > /sys/kernel/debug/$FAILTYPE/interval

    printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times

    echo -1 > /sys/kernel/debug/$FAILTYPE/times

    echo 0 > /sys/kernel/debug/$FAILTYPE/space

    echo 2 > /sys/kernel/debug/$FAILTYPE/verbose

    echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
@@ -308,7 +306,7 @@ Application Examples 
    echo N > /sys/kernel/debug/$FAILTYPE/task-filter

    echo 10 > /sys/kernel/debug/$FAILTYPE/probability

    echo 100 > /sys/kernel/debug/$FAILTYPE/interval

    printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times

    echo -1 > /sys/kernel/debug/$FAILTYPE/times

    echo 0 > /sys/kernel/debug/$FAILTYPE/space

    echo 2 > /sys/kernel/debug/$FAILTYPE/verbose

    echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
@@ -339,7 +337,7 @@ Application Examples 
    echo N > /sys/kernel/debug/$FAILTYPE/task-filter

    echo 100 > /sys/kernel/debug/$FAILTYPE/probability

    echo 0 > /sys/kernel/debug/$FAILTYPE/interval

    printf %#x -1 > /sys/kernel/debug/$FAILTYPE/times

    echo -1 > /sys/kernel/debug/$FAILTYPE/times

    echo 0 > /sys/kernel/debug/$FAILTYPE/space

    echo 1 > /sys/kernel/debug/$FAILTYPE/verbose

fs/debugfs/file.c

+22 −6
Original line number Diff line number Diff line
@@ -377,8 +377,8 @@ ssize_t debugfs_attr_read(struct file *file, char __user *buf, 
}

EXPORT_SYMBOL_GPL(debugfs_attr_read);



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

			 size_t len, loff_t *ppos)

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

			 size_t len, loff_t *ppos, bool is_signed)

{

	struct dentry *dentry = F_DENTRY(file);

	ssize_t ret;
@@ -386,12 +386,28 @@ ssize_t debugfs_attr_write(struct file *file, const char __user *buf, 
	ret = debugfs_file_get(dentry);

	if (unlikely(ret))

		return ret;

	if (is_signed)

		ret = simple_attr_write_signed(file, buf, len, ppos);

	else

		ret = simple_attr_write(file, buf, len, ppos);

	debugfs_file_put(dentry);

	return ret;

}



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

			 size_t len, loff_t *ppos)

{

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

}

EXPORT_SYMBOL_GPL(debugfs_attr_write);



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

			 size_t len, loff_t *ppos)

{

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

}

EXPORT_SYMBOL_GPL(debugfs_attr_write_signed);



static struct dentry *debugfs_create_mode_unsafe(const char *name, umode_t mode,

					struct dentry *parent, void *value,

					const struct file_operations *fops,
@@ -784,11 +800,11 @@ static int debugfs_atomic_t_get(void *data, u64 *val) 
	*val = atomic_read((atomic_t *)data);

	return 0;

}

DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,

DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t, debugfs_atomic_t_get,

			debugfs_atomic_t_set, "%lld\n");

DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t_ro, debugfs_atomic_t_get, NULL,

DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t_ro, debugfs_atomic_t_get, NULL,

			"%lld\n");

DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t_wo, NULL, debugfs_atomic_t_set,

DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t_wo, NULL, debugfs_atomic_t_set,

			"%lld\n");



/**

include/linux/debugfs.h

+17 −2
Original line number Diff line number Diff line
@@ -39,7 +39,7 @@ struct debugfs_regset32 { 


extern struct dentry *arch_debugfs_dir;



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

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

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

{									\

	__simple_attr_check_format(__fmt, 0ull);			\
@@ -50,10 +50,16 @@ static const struct file_operations __fops = { \ 
	.open	 = __fops ## _open,					\

	.release = simple_attr_release,					\

	.read	 = debugfs_attr_read,					\

	.write	 = debugfs_attr_write,					\

	.write	 = (__is_signed) ? debugfs_attr_write_signed : debugfs_attr_write,	\

	.llseek  = no_llseek,						\

}



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

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



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

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



typedef struct vfsmount *(*debugfs_automount_t)(struct dentry *, void *);



#if defined(CONFIG_DEBUG_FS)
@@ -96,6 +102,8 @@ ssize_t debugfs_attr_read(struct file *file, char __user *buf, 
			size_t len, loff_t *ppos);

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

			size_t len, loff_t *ppos);

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

			size_t len, loff_t *ppos);



struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,

                struct dentry *new_dir, const char *new_name);
@@ -245,6 +253,13 @@ static inline ssize_t debugfs_attr_write(struct file *file, 
	return -ENODEV;

}



static inline ssize_t debugfs_attr_write_signed(struct file *file,

					const char __user *buf,

					size_t len, loff_t *ppos)

{

	return -ENODEV;

}



static inline struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,

                struct dentry *new_dir, char *new_name)

{