[PATCH 6.0 0147/1073] debugfs: fix error when writing negative value to atomic_t debugfs file

Greg Kroah-Hartman
2022-12-28T15:12:04Z

From: Akinobu Mita <akinobu.mita@gmail.com>

[ 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: 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>
---
.../fault-injection/fault-injection.rst | 10 +++----
fs/debugfs/file.c | 28 +++++++++++++++----
include/linux/debugfs.h | 19 +++++++++++--
3 files changed, 43 insertions(+), 14 deletions(-)

diff --git a/Documentation/fault-injection/fault-injection.rst b/Documentation/fault-injection/fault-injection.rst
index 17779a2772e5..5f6454b9dbd4 100644
--- a/Documentation/fault-injection/fault-injection.rst
+++ b/Documentation/fault-injection/fault-injection.rst
@@ -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:

@@ -284,7 +282,7 @@ 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/$FAILTYPE/verbose
echo Y > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
@@ -338,7 +336,7 @@ 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/$FAILTYPE/verbose
echo Y > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
@@ -369,7 +367,7 @@ 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

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 950c63fa4d0b..38930d9b0bb7 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -378,8 +378,8 @@ 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;
@@ -387,12 +387,28 @@ ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
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,
@@ -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");

/**
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index f60674692d36..ea2d919fd9c7 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -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); \
@@ -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)
@@ -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);
@@ -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)
{
--
2.35.1