The suffix of the input buffer is truncated in {enabled,defrag}_store().
With that, the illegal settings can be accepted, as the following example
shows.
# cat /sys/kernel/mm/transparent_hugepage/enabled
always [madvise] never
# echo neveroff > /sys/kernel/mm/transparent_hugepage/enabled
# cat /sys/kernel/mm/transparent_hugepage/enabled
always madvise [never]
This reworks {enabled,defrag}_store() to fix the issue and make the code
a bit more extendible. With this applied, the illegal settings will be
rejected:
# echo neveroff > /sys/kernel/mm/transparent_hugepage/enabled
sh: write error: Invalid argument
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
mm/huge_memory.c | 114 ++++++++++++++++++++++++++---------------------
1 file changed, 62 insertions(+), 52 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a88093213674..7bd573f1631d 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -160,6 +160,15 @@ static struct shrinker huge_zero_page_shrinker = {
};
#ifdef CONFIG_SYSFS
+static const char * const enabled_strings[] = {
+ "always", "madvise", "never"
+};
+static unsigned int enabled_bits[] = {
+ TRANSPARENT_HUGEPAGE_FLAG,
+ TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ UINT_MAX
+};
+
static ssize_t enabled_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -175,29 +184,29 @@ static ssize_t enabled_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
- ssize_t ret = count;
-
- if (!memcmp("always", buf,
- min(sizeof("always")-1, count))) {
- clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
- set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
- } else if (!memcmp("madvise", buf,
- min(sizeof("madvise")-1, count))) {
- clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
- set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
- } else if (!memcmp("never", buf,
- min(sizeof("never")-1, count))) {
- clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
- } else
- ret = -EINVAL;
+ int i, ret;
- if (ret > 0) {
- int err = start_stop_khugepaged();
- if (err)
- ret = err;
+ for (i = 0; i < ARRAY_SIZE(enabled_strings); i++) {
+ if ((count - 1) == strlen(enabled_strings[i]) &&
+ !memcmp(buf, enabled_strings[i], count - 1))
+ break;
}
- return ret;
+
+ if (i >= ARRAY_SIZE(enabled_strings))
+ return -EINVAL;
+
+ clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
+ &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+ if (enabled_bits[i] != UINT_MAX)
+ set_bit(enabled_bits[i], &transparent_hugepage_flags);
+
+ ret = start_stop_khugepaged();
+ if (ret)
+ return ret;
+
+ return count;
}
static struct kobj_attribute enabled_attr =
__ATTR(enabled, 0644, enabled_show, enabled_store);
@@ -232,6 +241,17 @@ ssize_t single_hugepage_flag_store(struct kobject *kobj,
return count;
}
+static const char * const defrag_strings[] = {
+ "always", "defer+madvise", "defer", "madvise", "never"
+};
+static unsigned int defrag_bits[] = {
+ TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
+ TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
+ TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
+ TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
+ UINT_MAX
+};
+
static ssize_t defrag_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -250,39 +270,29 @@ static ssize_t defrag_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
- if (!memcmp("always", buf,
- min(sizeof("always")-1, count))) {
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
- set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
- } else if (!memcmp("defer+madvise", buf,
- min(sizeof("defer+madvise")-1, count))) {
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
- set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
- } else if (!memcmp("defer", buf,
- min(sizeof("defer")-1, count))) {
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
- set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
- } else if (!memcmp("madvise", buf,
- min(sizeof("madvise")-1, count))) {
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
- set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
- } else if (!memcmp("never", buf,
- min(sizeof("never")-1, count))) {
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
- clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
- } else
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(defrag_strings); i++) {
+ if ((count - 1) == strlen(defrag_strings[i]) &&
+ !memcmp(buf, defrag_strings[i], count - 1))
+ break;
+ }
+
+ if (i >= ARRAY_SIZE(defrag_strings))
return -EINVAL;
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
+ &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
+ &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
+ &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+
+ if (defrag_bits[i] != UINT_MAX)
+ set_bit(defrag_bits[i], &transparent_hugepage_flags);
+
return count;
}
static struct kobj_attribute defrag_attr =
--
2.23.0
