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
488dac0c9237 ("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
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.

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: 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>

diff --git a/fs/libfs.c b/fs/libfs.c
index 682d56345a1cfeb3977e9d66b00017540f7fb492..aada4e7c871328ab9d775a8febd771ae41c5b3cf 100644 (file)
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -995,8 +995,8 @@ out:
 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;
@@ -1017,7 +1017,10 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf,
                goto out;
 
        attr->set_buf[size] = '\0';
-       ret = kstrtoull(attr->set_buf, 0, &val);
+       if (is_signed)
+               ret = kstrtoll(attr->set_buf, 0, &val);
+       else
+               ret = kstrtoull(attr->set_buf, 0, &val);
        if (ret)
                goto out;
        ret = attr->set(attr->data, val);
@@ -1027,8 +1030,21 @@ out:
        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

diff --git a/include/linux/fs.h b/include/linux/fs.h
index e654435f16512c122f176d0ab447925ae94f75fc..452700c5fa1df66cf3a042abc7561cef0caf3231 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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);