Commit 54e948c6 authored Jun 28, 2021 by Dan Carpenter Committed by Linus Torvalds Jun 29, 2021

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: a860f6eb ("ocfs2: sysfile interfaces for online file check")
Fixes: 74ae4e10 ("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>

parent 74ef829e

fs/ocfs2/filecheck.c

+1 −5

Original line number	Diff line number	Diff line
		@@ -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;

fs/ocfs2/stackglue.c

+2 −6

Original line number	Diff line number	Diff line
		@@ -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);