Skip to content

Commit

Permalink
debugfs: fix error when writing negative value to atomic_t debugfs file
Browse files Browse the repository at this point in the history 
[ Upstream commit d472cf7 ]

The simple attribute files do not accept a negative value since the commit
488dac0 ("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: 488dac0 ("libfs: fix error cast of negative value in simple_attr_write()")
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Reported-by: Zhao Gongyi <zhaogongyi@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Greg 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
  • Loading branch information
@mita @gregkh
mita authored and gregkh committed Dec 31, 2022
1 parent 7e8e8cc commit 4662d8e
Show file tree
Hide file tree
Showing 3 changed files with 43 additions and 14 deletions.
10 changes: 4 additions & 6 deletions Documentation/fault-injection/fault-injection.rst
View file
Expand Up @@ -83,9 +83,7 @@ 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:

Expand Down Expand Up @@ -277,7 +275,7 @@ 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
Expand Down Expand Up @@ -331,7 +329,7 @@ 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
Expand Down Expand Up @@ -362,7 +360,7 @@ 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

Expand Down
28 changes: 22 additions & 6 deletions fs/debugfs/file.c
View file
Expand Up @@ -378,21 +378,37 @@ 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;

ret = debugfs_file_get(dentry);
if (unlikely(ret))
return ret;
ret = simple_attr_write(file, buf, len, ppos);
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,
Expand Down Expand Up @@ -738,11 +754,11 @@ 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");

/**
Expand Down
19 changes: 17 additions & 2 deletions include/linux/debugfs.h
View file
Expand Up @@ -45,7 +45,7 @@ struct debugfs_u32_array {

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); \
Expand All @@ -56,10 +56,16 @@ 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)
Expand Down Expand Up @@ -102,6 +108,8 @@ 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);
Expand Down Expand Up @@ -254,6 +262,13 @@ 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)
{
Expand Down

0 comments on commit 4662d8e

Please sign in to comment.