[PATCH 1/2] topology: use bin_attribute to avoid buff overflow
From: Tian Tao
Date: Mon May 31 2021 - 22:57:13 EST
Reading sys/devices/system/cpu/cpuX/topology/ returns cpu topology.
However, the size of this file is limited to PAGE_SIZE because of the
limitation for sysfs attribute. so we use bin_attribute instead of
attribute to avoid NR_CPUS too big to cause buff overflow.
This patch is based on the following discussion.
https://www.spinics.net/lists/linux-doc/msg95921.html
Signed-off-by: Tian Tao <tiantao6@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
---
drivers/base/topology.c | 115 ++++++++++++++++++++++++++----------------------
include/linux/bitmap.h | 3 ++
include/linux/cpumask.h | 25 +++++++++++
lib/bitmap.c | 34 ++++++++++++++
4 files changed, 125 insertions(+), 52 deletions(-)
diff --git a/drivers/base/topology.c b/drivers/base/topology.c
index 4d254fc..013edbb 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -21,25 +21,27 @@ static ssize_t name##_show(struct device *dev, \
return sysfs_emit(buf, "%d\n", topology_##name(dev->id)); \
}
-#define define_siblings_show_map(name, mask) \
-static ssize_t name##_show(struct device *dev, \
- struct device_attribute *attr, char *buf) \
-{ \
- return cpumap_print_to_pagebuf(false, buf, topology_##mask(dev->id));\
+#define define_siblings_read_func(name, mask) \
+static ssize_t name##_read(struct file *file, struct kobject *kobj, \
+ struct bin_attribute *attr, char *buf, \
+ loff_t off, size_t count) \
+{ \
+ struct device *dev = kobj_to_dev(kobj); \
+ \
+ return cpumap_print_to_buf(false, buf, topology_##mask(dev->id), \
+ off, count); \
+} \
+ \
+static ssize_t name##_list_read(struct file *file, struct kobject *kobj, \
+ struct bin_attribute *attr, char *buf, \
+ loff_t off, size_t count) \
+{ \
+ struct device *dev = kobj_to_dev(kobj); \
+ \
+ return cpumap_print_to_buf(true, buf, topology_##mask(dev->id), \
+ off, count); \
}
-#define define_siblings_show_list(name, mask) \
-static ssize_t name##_list_show(struct device *dev, \
- struct device_attribute *attr, \
- char *buf) \
-{ \
- return cpumap_print_to_pagebuf(true, buf, topology_##mask(dev->id));\
-}
-
-#define define_siblings_show_func(name, mask) \
- define_siblings_show_map(name, mask); \
- define_siblings_show_list(name, mask)
-
define_id_show_func(physical_package_id);
static DEVICE_ATTR_RO(physical_package_id);
@@ -49,71 +51,80 @@ static DEVICE_ATTR_RO(die_id);
define_id_show_func(core_id);
static DEVICE_ATTR_RO(core_id);
-define_siblings_show_func(thread_siblings, sibling_cpumask);
-static DEVICE_ATTR_RO(thread_siblings);
-static DEVICE_ATTR_RO(thread_siblings_list);
+define_siblings_read_func(thread_siblings, sibling_cpumask);
+static BIN_ATTR_RO(thread_siblings, 0);
+static BIN_ATTR_RO(thread_siblings_list, 0);
-define_siblings_show_func(core_cpus, sibling_cpumask);
-static DEVICE_ATTR_RO(core_cpus);
-static DEVICE_ATTR_RO(core_cpus_list);
+define_siblings_read_func(core_cpus, sibling_cpumask);
+static BIN_ATTR_RO(core_cpus, 0);
+static BIN_ATTR_RO(core_cpus_list, 0);
-define_siblings_show_func(core_siblings, core_cpumask);
-static DEVICE_ATTR_RO(core_siblings);
-static DEVICE_ATTR_RO(core_siblings_list);
+define_siblings_read_func(core_siblings, core_cpumask);
+static BIN_ATTR_RO(core_siblings, 0);
+static BIN_ATTR_RO(core_siblings_list, 0);
-define_siblings_show_func(die_cpus, die_cpumask);
-static DEVICE_ATTR_RO(die_cpus);
-static DEVICE_ATTR_RO(die_cpus_list);
+define_siblings_read_func(die_cpus, die_cpumask);
+static BIN_ATTR_RO(die_cpus, 0);
+static BIN_ATTR_RO(die_cpus_list, 0);
-define_siblings_show_func(package_cpus, core_cpumask);
-static DEVICE_ATTR_RO(package_cpus);
-static DEVICE_ATTR_RO(package_cpus_list);
+define_siblings_read_func(package_cpus, core_cpumask);
+static BIN_ATTR_RO(package_cpus, 0);
+static BIN_ATTR_RO(package_cpus_list, 0);
#ifdef CONFIG_SCHED_BOOK
define_id_show_func(book_id);
static DEVICE_ATTR_RO(book_id);
-define_siblings_show_func(book_siblings, book_cpumask);
-static DEVICE_ATTR_RO(book_siblings);
-static DEVICE_ATTR_RO(book_siblings_list);
+define_siblings_read_func(book_siblings, book_cpumask);
+static BIN_ATTR_RO(book_siblings, 0);
+static BIN_ATTR_RO(book_siblings_list, 0);
#endif
#ifdef CONFIG_SCHED_DRAWER
define_id_show_func(drawer_id);
static DEVICE_ATTR_RO(drawer_id);
-define_siblings_show_func(drawer_siblings, drawer_cpumask);
-static DEVICE_ATTR_RO(drawer_siblings);
-static DEVICE_ATTR_RO(drawer_siblings_list);
+define_siblings_read_func(drawer_siblings, drawer_cpumask);
+static BIN_ATTR_RO(drawer_siblings, 0);
+static BIN_ATTR_RO(drawer_siblings_list, 0);
#endif
+static struct bin_attribute *bin_attrs[] = {
+ &bin_attr_core_cpus,
+ &bin_attr_core_cpus_list,
+ &bin_attr_thread_siblings,
+ &bin_attr_thread_siblings_list,
+ &bin_attr_core_siblings,
+ &bin_attr_core_siblings_list,
+ &bin_attr_die_cpus,
+ &bin_attr_die_cpus_list,
+ &bin_attr_package_cpus,
+ &bin_attr_package_cpus_list,
+#ifdef CONFIG_SCHED_BOOK
+ &bin_attr_book_siblings,
+ &bin_attr_book_siblings_list,
+#endif
+#ifdef CONFIG_SCHED_DRAWER
+ &bin_attr_drawer_siblings,
+ &bin_attr_drawer_siblings_list,
+#endif
+ NULL,
+};
+
static struct attribute *default_attrs[] = {
&dev_attr_physical_package_id.attr,
&dev_attr_die_id.attr,
&dev_attr_core_id.attr,
- &dev_attr_thread_siblings.attr,
- &dev_attr_thread_siblings_list.attr,
- &dev_attr_core_cpus.attr,
- &dev_attr_core_cpus_list.attr,
- &dev_attr_core_siblings.attr,
- &dev_attr_core_siblings_list.attr,
- &dev_attr_die_cpus.attr,
- &dev_attr_die_cpus_list.attr,
- &dev_attr_package_cpus.attr,
- &dev_attr_package_cpus_list.attr,
#ifdef CONFIG_SCHED_BOOK
&dev_attr_book_id.attr,
- &dev_attr_book_siblings.attr,
- &dev_attr_book_siblings_list.attr,
#endif
#ifdef CONFIG_SCHED_DRAWER
&dev_attr_drawer_id.attr,
- &dev_attr_drawer_siblings.attr,
- &dev_attr_drawer_siblings_list.attr,
#endif
NULL
};
static const struct attribute_group topology_attr_group = {
.attrs = default_attrs,
+ .bin_attrs = bin_attrs,
.name = "topology"
};
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 70a9324..bc401bd9b 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -219,6 +219,9 @@ extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int
extern int bitmap_print_to_pagebuf(bool list, char *buf,
const unsigned long *maskp, int nmaskbits);
+extern int bitmap_print_to_buf(bool list, char *buf,
+ const unsigned long *maskp, int nmaskbits, loff_t off, size_t count);
+
#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 383684e..e4810b3e 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -928,6 +928,31 @@ cpumap_print_to_pagebuf(bool list, char *buf, const struct cpumask *mask)
nr_cpu_ids);
}
+/**
+ * cpumap_print_to_buf - copies the cpumask into the buffer either
+ * as comma-separated list of cpus or hex values of cpumask
+ * @list: indicates whether the cpumap must be list
+ * @mask: the cpumask to copy
+ * @buf: the buffer to copy into
+ * @off: the offset that buffer to copy into
+ * @count: the count thatbuffer to copy into
+ *
+ * the role of cpumap_print_to_buf and cpumap_print_to_pagebuf is
+ * the same, the difference is that the second parameter of
+ * bitmap_print_to_buf can be more than one pagesize.
+ *
+ * Returns the length of the (null-terminated) @buf string, zero if
+ * nothing is copied.
+ */
+
+static inline ssize_t
+cpumap_print_to_buf(bool list, char *buf, const struct cpumask *mask,
+ loff_t off, size_t count)
+{
+ return bitmap_print_to_buf(list, buf, cpumask_bits(mask),
+ nr_cpu_ids, off, count);
+}
+
#if NR_CPUS <= BITS_PER_LONG
#define CPU_MASK_ALL \
(cpumask_t) { { \
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 75006c4..5bf89f1 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -460,6 +460,40 @@ int bitmap_parse_user(const char __user *ubuf,
EXPORT_SYMBOL(bitmap_parse_user);
/**
+ * bitmap_print_to_buf - convert bitmap to list or hex format ASCII string
+ * @list: indicates whether the bitmap must be list
+ * @buf: page aligned buffer into which string is placed
+ * @maskp: pointer to bitmap to convert
+ * @nmaskbits: size of bitmap, in bits
+ * @off: offset in buf
+ * @count: count that already output
+ *
+ * the role of bitmap_print_to_buf and bitmap_print_to_pagebuf is
+ * the same, the difference is that the second parameter of
+ * bitmap_print_to_buf can be more than one pagesize.
+ */
+int bitmap_print_to_buf(bool list, char *buf, const unsigned long *maskp,
+ int nmaskbits, loff_t off, size_t count)
+{
+ int len, size;
+ void *data;
+ char *fmt = list ? "%*pbl\n" : "%*pb\n";
+
+ len = snprintf(NULL, 0, fmt, nmaskbits, maskp);
+
+ data = kvmalloc(len+1, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ size = scnprintf(data, len+1, fmt, nmaskbits, maskp);
+ size = memory_read_from_buffer(buf, count, &off, data, size);
+ kvfree(data);
+
+ return size;
+}
+EXPORT_SYMBOL(bitmap_print_to_buf);
+
+/**
* bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
* @list: indicates whether the bitmap must be list
* @buf: page aligned buffer into which string is placed
--
2.7.4