linux-kernel - [PATCH v2] f2fs: fix to avoid accessing uninitialized field of inode page in is

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Date:   Tue, 10 Sep 2019 09:14:16 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>,
        Chao Yu <yuchao0@...wei.com>
Subject: [PATCH v2] f2fs: fix to avoid accessing uninitialized field of inode page in is_alive()

If inode is newly created, inode page may not synchronize with inode cache,
so fields like .i_inline or .i_extra_isize could be wrong, in below call
path, we may access such wrong fields, result in failing to migrate valid
target block.

Thread A				Thread B
- f2fs_create
 - f2fs_add_link
  - f2fs_add_dentry
   - f2fs_init_inode_metadata
    - f2fs_add_inline_entry
     - f2fs_new_inode_page
     - f2fs_put_page
     : inode page wasn't updated with inode cache
					- gc_data_segment
					 - is_alive
					  - f2fs_get_node_page
					  - datablock_addr
					   - offset_in_addr
					   : access uninitialized fields

Fixes: 7a2af766af15 ("f2fs: enhance on-disk inode structure scalability")
Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
v2:
- update inode page before f2fs_put_page()
 fs/f2fs/dir.c    | 5 +++++
 fs/f2fs/inline.c | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 7afbf8f5ab08..4033778bcbbf 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -682,6 +682,11 @@ int f2fs_add_regular_entry(struct inode *dir, const struct qstr *new_name,
 
 	if (inode) {
 		f2fs_i_pino_write(inode, dir->i_ino);
+
+		/* synchronize inode page's data from inode cache */
+		if (is_inode_flag_set(inode, FI_NEW_INODE))
+			f2fs_update_inode(inode, page);
+
 		f2fs_put_page(page, 1);
 	}
 
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
index 16ebdd4d1f2c..896db0416f0e 100644
--- a/fs/f2fs/inline.c
+++ b/fs/f2fs/inline.c
@@ -589,6 +589,11 @@ int f2fs_add_inline_entry(struct inode *dir, const struct qstr *new_name,
 	/* we don't need to mark_inode_dirty now */
 	if (inode) {
 		f2fs_i_pino_write(inode, dir->i_ino);
+
+		/* synchronize inode page's data from inode cache */
+		if (is_inode_flag_set(inode, FI_NEW_INODE))
+			f2fs_update_inode(inode, page);
+
 		f2fs_put_page(page, 1);
 	}
 
-- 
2.18.0.rc1