linux-kernel - [PATCH] jffs2: move jffs2_init_inode_info() just after allocating inode

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Message-ID: <20200106080411.41394-1-yi.zhang@huawei.com>
Date:   Mon, 6 Jan 2020 16:04:11 +0800
From:   "zhangyi (F)" <yi.zhang@...wei.com>
To:     <viro@...iv.linux.org.uk>
CC:     <ast@...nel.org>, <daniel@...earbox.net>,
        <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mtd@...ts.infradead.org>, <yi.zhang@...wei.com>,
        <yihuaijie@...wei.com>, <zhongguohua1@...wei.com>,
        <chenjie6@...wei.com>
Subject: [PATCH] jffs2: move jffs2_init_inode_info() just after allocating inode

After commit 4fdcfab5b553 ("jffs2: fix use-after-free on symlink
traversal"), it expose a freeing uninitialized memory problem due to
this commit move the operaion of freeing f->target to
jffs2_i_callback(), which may not be initialized in some error path of
allocating jffs2 inode (eg: jffs2_iget()->iget_locked()->
destroy_inode()->..->jffs2_i_callback()->kfree(f->target)).

Fix this by initialize the jffs2_inode_info just after allocating it.

Reported-by: Guohua Zhong <zhongguohua1@...wei.com>
Reported-by: Huaijie Yi <yihuaijie@...wei.com>
Signed-off-by: zhangyi (F) <yi.zhang@...wei.com>
Cc: stable@...r.kernel.org
---
 fs/jffs2/fs.c    | 2 --
 fs/jffs2/super.c | 2 ++
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
index ab8cdd9e9325..50a9df7d43a5 100644
--- a/fs/jffs2/fs.c
+++ b/fs/jffs2/fs.c
@@ -270,7 +270,6 @@ struct inode *jffs2_iget(struct super_block *sb, unsigned long ino)
 	f = JFFS2_INODE_INFO(inode);
 	c = JFFS2_SB_INFO(inode->i_sb);
 
-	jffs2_init_inode_info(f);
 	mutex_lock(&f->sem);
 
 	ret = jffs2_do_read_inode(c, f, inode->i_ino, &latest_node);
@@ -438,7 +437,6 @@ struct inode *jffs2_new_inode (struct inode *dir_i, umode_t mode, struct jffs2_r
 		return ERR_PTR(-ENOMEM);
 
 	f = JFFS2_INODE_INFO(inode);
-	jffs2_init_inode_info(f);
 	mutex_lock(&f->sem);
 
 	memset(ri, 0, sizeof(*ri));
diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index 0e6406c4f362..90373898587f 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c
@@ -42,6 +42,8 @@ static struct inode *jffs2_alloc_inode(struct super_block *sb)
 	f = kmem_cache_alloc(jffs2_inode_cachep, GFP_KERNEL);
 	if (!f)
 		return NULL;
+
+	jffs2_init_inode_info(f);
 	return &f->vfs_inode;
 }
 
-- 
2.17.2