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authorChao Yu <yuchao0@huawei.com>2018-05-28 16:57:32 +0800
committerJaegeuk Kim <jaegeuk@kernel.org>2018-05-31 11:31:52 -0700
commit250dbf515192811025c4f3ba764a985f9b95be8e (patch)
tree387694a4b8840e81b04b601143333a6a7fdeaedf /fs/f2fs
parentaec2f729fca13661e9bc651839ae23bf8367195a (diff)
f2fs: fix to avoid race during access gc_thread pointer
Thread A Thread B - f2fs_remount - stop_gc_thread - f2fs_sbi_store sbi->gc_thread = NULL; access sbi->gc_thread->gc_* Previously, we allocate memory for sbi->gc_thread based on background gc thread mount option, the memory can be released if we turn off that mount option, but still there are several places access gc_thread pointer without considering race condition, result in NULL point dereference. In order to fix this issue, use sb->s_umount to exclude those operations. Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs')
-rw-r--r--fs/f2fs/sysfs.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index dd940d156af6..ac3ea6044936 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -165,7 +165,7 @@ static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
return snprintf(buf, PAGE_SIZE, "%u\n", *ui);
}
-static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
+static ssize_t __f2fs_sbi_store(struct f2fs_attr *a,
struct f2fs_sb_info *sbi,
const char *buf, size_t count)
{
@@ -278,6 +278,23 @@ out:
return count;
}
+static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
+ struct f2fs_sb_info *sbi,
+ const char *buf, size_t count)
+{
+ ssize_t ret;
+ bool gc_entry = (!strcmp(a->attr.name, "gc_urgent") ||
+ a->struct_type == GC_THREAD);
+
+ if (gc_entry)
+ down_read(&sbi->sb->s_umount);
+ ret = __f2fs_sbi_store(a, sbi, buf, count);
+ if (gc_entry)
+ up_read(&sbi->sb->s_umount);
+
+ return ret;
+}
+
static ssize_t f2fs_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{