ocfs2: fix snprintf() checking

The snprintf() function returns the number of bytes which would have been
printed if the buffer was large enough.  In other words it can return ">=
remain" but this code assumes it returns "== remain".

The run time impact of this bug is not very severe.  The next iteration
through the loop would trigger a WARN() when we pass a negative limit to
snprintf().  We would then return success instead of -E2BIG.

The kernel implementation of snprintf() will never return negatives so
there is no need to check and I have deleted that dead code.

Link: https://lkml.kernel.org/r/20210511135350.GV1955@kadam
Fixes: a860f6eb4c6a ("ocfs2: sysfile interfaces for online file check")
Fixes: 74ae4e104dfc ("ocfs2: Create stack glue sysfs files.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ocfs2/filecheck.c b/fs/ocfs2/filecheck.c
index 90b8d300c1eea8079b34e56f48743a634d8a5072..de56e6231af87f41c4d4da444d3c0013d9bb06fa 100644 (file)
--- a/fs/ocfs2/filecheck.c
+++ b/fs/ocfs2/filecheck.c
@@ -326,11 +326,7 @@ static ssize_t ocfs2_filecheck_attr_show(struct kobject *kobj,
                ret = snprintf(buf + total, remain, "%lu\t\t%u\t%s\n",
                               p->fe_ino, p->fe_done,
                               ocfs2_filecheck_error(p->fe_status));
-               if (ret < 0) {
-                       total = ret;
-                       break;
-               }
-               if (ret == remain) {
+               if (ret >= remain) {
                        /* snprintf() didn't fit */
                        total = -E2BIG;
                        break;

diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
index d50e8b8dfea47e1c43439ec8011a2e4e0a59d50c..16f1bfc407f2a18124fbd3288c8518f24931d90e 100644 (file)
--- a/fs/ocfs2/stackglue.c
+++ b/fs/ocfs2/stackglue.c
@@ -500,11 +500,7 @@ static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
        list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
                ret = snprintf(buf, remain, "%s\n",
                               p->sp_name);
-               if (ret < 0) {
-                       total = ret;
-                       break;
-               }
-               if (ret == remain) {
+               if (ret >= remain) {
                        /* snprintf() didn't fit */
                        total = -E2BIG;
                        break;
@@ -531,7 +527,7 @@ static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
        if (active_stack) {
                ret = snprintf(buf, PAGE_SIZE, "%s\n",
                               active_stack->sp_name);
-               if (ret == PAGE_SIZE)
+               if (ret >= PAGE_SIZE)
                        ret = -E2BIG;
        }
        spin_unlock(&ocfs2_stack_lock);