+ ocfs2-fix-snprintf-checking.patch added to -mm tree

+ ocfs2-fix-snprintf-checking.patch added to -mm tree

[akpm]

The patch titled
     Subject: ocfs2: fix snprintf() checking
has been added to the -mm tree.  Its filename is
     ocfs2-fix-snprintf-checking.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/ocfs2-fix-snprintf-checking.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-fix-snprintf-checking.patch

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------------------------------------------------------
From: Dan Carpenter <dan.carpenter@oracle.com>
Subject: 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>
---

 fs/ocfs2/filecheck.c |    6 +-----
 fs/ocfs2/stackglue.c |    8 ++------
 2 files changed, 3 insertions(+), 11 deletions(-)

--- a/fs/ocfs2/filecheck.c~ocfs2-fix-snprintf-checking
+++ a/fs/ocfs2/filecheck.c
@@ -326,11 +326,7 @@ static ssize_t ocfs2_filecheck_attr_show
 		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;
--- a/fs/ocfs2/stackglue.c~ocfs2-fix-snprintf-checking
+++ a/fs/ocfs2/stackglue.c
@@ -500,11 +500,7 @@ static ssize_t ocfs2_loaded_cluster_plug
 	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_plug
 	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);
_

Patches currently in -mm which might be from dan.carpenter@oracle.com are

ocfs2-fix-snprintf-checking.patch