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Tue, 11 May 2021 07:16:30 +0000 Received: from aserp3030.oracle.com (aserp3030.oracle.com [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 14B7GUGv077990 for ; Tue, 11 May 2021 07:16:30 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 38e5pwqr8w-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 11 May 2021 07:16:30 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 14B7GRpq029227; Tue, 11 May 2021 07:16:27 GMT Received: from mwanda (/102.36.221.92) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 11 May 2021 00:16:27 -0700 Date: Tue, 11 May 2021 10:16:20 +0300 From: Dan Carpenter To: Mark Fasheh Message-ID: MIME-Version: 1.0 Content-Disposition: inline X-Mailer: git-send-email haha only kidding Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com Subject: [Ocfs2-devel] [PATCH] ocfs2: fix snprintf() checking X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9980 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 phishscore=0 adultscore=0 bulkscore=0 mlxscore=0 suspectscore=0 malwarescore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105110054 X-Proofpoint-GUID: _h-9RWwtPpEyFigp64TF0tQ_J81bAdkL X-Proofpoint-ORIG-GUID: _h-9RWwtPpEyFigp64TF0tQ_J81bAdkL X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9980 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 priorityscore=1501 suspectscore=0 clxscore=1011 bulkscore=0 adultscore=0 impostorscore=0 spamscore=0 phishscore=0 mlxlogscore=999 mlxscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105110054 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 Reviewed-by: Joseph Qi --- 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);