Patch "fat: fix using uninitialized fields of fat_inode/fsinfo_inode" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

fat: fix using uninitialized fields of fat_inode/fsinfo_inode

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
fat-fix-using-uninitialized-fields-of-fat_inode-fsinfo_inode.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: OGAWA Hirofumi <[email protected]>
Date: Thu, 9 Mar 2017 16:17:37 -0800
Subject: fat: fix using uninitialized fields of fat_inode/fsinfo_inode

From: OGAWA Hirofumi <[email protected]>

commit c0d0e351285161a515396b7b1ee53ec9ffd97e3c upstream.

Recently fallocate patch was merged and it uses MSDOS_I(inode)->mmu_private at fat_evict_inode(). However, fat_inode/fsinfo_inode that was introduced in past didn't initialize MSDOS_I(inode) properly.

With those combinations, it became the cause of accessing random entry in FAT area.

---
 fs/fat/inode.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

@@ -1269,6 +1269,16 @@ out:
 	return 0;
 }
 
+static void fat_dummy_inode_init(struct inode *inode)
+{
+	/* Initialize this dummy inode to work as no-op. */
+	MSDOS_I(inode)->mmu_private = 0;
+	MSDOS_I(inode)->i_start = 0;
+	MSDOS_I(inode)->i_logstart = 0;
+	MSDOS_I(inode)->i_attrs = 0;
+	MSDOS_I(inode)->i_pos = 0;
+}
+
 static int fat_read_root(struct inode *inode)
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);

@@ -1713,12 +1723,13 @@ int fat_fill_super(struct super_block *s
 	fat_inode = new_inode(sb);
 	if (!fat_inode)
 		goto out_fail;
-	MSDOS_I(fat_inode)->i_pos = 0;
+	fat_dummy_inode_init(fat_inode);
 	sbi->fat_inode = fat_inode;
 
 	fsinfo_inode = new_inode(sb);
 	if (!fsinfo_inode)
 		goto out_fail;
+	fat_dummy_inode_init(fsinfo_inode);
 	fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
 	sbi->fsinfo_inode = fsinfo_inode;
 	insert_inode_hash(fsinfo_inode);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/fat-fix-using-uninitialized-fields-of-fat_inode-fsinfo_inode.patch