From: Dan Carpenter <dan.carpenter@oracle.com>
To: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>,
Joseph Qi <joseph.qi@linux.alibaba.com>,
Andrew Morton <akpm@linux-foundation.org>, Gang He <ghe@suse.com>,
ocfs2-devel@oss.oracle.com, linux-kernel@vger.kernel.org,
kernel-janitors@vger.kernel.org
Subject: [PATCH] ocfs2: fix snprintf() checking
Date: Tue, 11 May 2021 10:16:20 +0300 [thread overview]
Message-ID: <YJovRPdOiaU6I+JK@mwanda> (raw)
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.
Fixes: a860f6eb4c6a ("ocfs2: sysfile interfaces for online file check")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
fs/ocfs2/filecheck.c | 6 +-----
fs/ocfs2/stackglue.c | 8 ++------
2 files changed, 3 insertions(+), 11 deletions(-)
diff --git a/fs/ocfs2/filecheck.c b/fs/ocfs2/filecheck.c
index 90b8d300c1ee..de56e6231af8 100644
--- 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 d50e8b8dfea4..16f1bfc407f2 100644
--- 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);
--
2.30.2
next reply other threads:[~2021-05-11 7:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 7:16 Dan Carpenter [this message]
2021-05-11 12:54 ` [PATCH] ocfs2: fix snprintf() checking Joseph Qi
2021-05-11 13:52 ` Dan Carpenter
2021-05-11 13:53 ` [PATCH v2] " Dan Carpenter
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