From: Jia-Ju Bai <baijiaju1990@gmail.com>
Date: Sun, 6 Oct 2019 17:57:57 -0700
Subject: fs: ocfs2: fix a possible null-pointer dereference in
 ocfs2_info_scan_inode_alloc()
Git-commit: 2abb7d3b12d007c30193f48bebed781009bebdd2
Patch-mainline: 5.4-rc3
References: bnc#1151927 5.3.9

In ocfs2_info_scan_inode_alloc(), there is an if statement on line 283
to check whether inode_alloc is NULL:

    if (inode_alloc)

When inode_alloc is NULL, it is used on line 287:

    ocfs2_inode_lock(inode_alloc, &bh, 0);
        ocfs2_inode_lock_full_nested(inode, ...)
            struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

Thus, a possible null-pointer dereference may occur.

To fix this bug, inode_alloc is checked on line 286.

This bug is found by a static analysis tool STCheck written by us.

Link: http://lkml.kernel.org/r/20190726033717.32359-1-baijiaju1990@gmail.com
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.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: Jiri Slaby <jslaby@suse.cz>
---
 fs/ocfs2/ioctl.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -283,7 +283,7 @@ static int ocfs2_info_scan_inode_alloc(s
 	if (inode_alloc)
 		inode_lock(inode_alloc);
 
-	if (o2info_coherent(&fi->ifi_req)) {
+	if (inode_alloc && o2info_coherent(&fi->ifi_req)) {
 		status = ocfs2_inode_lock(inode_alloc, &bh, 0);
 		if (status < 0) {
 			mlog_errno(status);