| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.4 182/348] ocfs2: fix snprintf() checking | Date | Mon, 12 Jul 2021 08:09:26 +0200 |
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From: Dan Carpenter <dan.carpenter@oracle.com>
[ Upstream commit 54e948c60cc843b6e84dc44496edc91f51d2a28e ]
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> Signed-off-by: Sasha Levin <sashal@kernel.org> --- 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 50f11bfdc8c2..82a3edc4aea4 100644 --- a/fs/ocfs2/filecheck.c +++ b/fs/ocfs2/filecheck.c @@ -328,11 +328,7 @@ 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 8aa6a667860c..188038760136 100644 --- a/fs/ocfs2/stackglue.c +++ b/fs/ocfs2/stackglue.c @@ -502,11 +502,7 @@ 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; @@ -533,7 +529,7 @@ 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
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