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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH 4.16 034/161] ext2: fix a block leak
Date:   Thu, 24 May 2018 11:37:39 +0200
Message-Id: <20180524093022.449554719@linuxfoundation.org>
In-Reply-To: <20180524093018.331893860@linuxfoundation.org>
References: <20180524093018.331893860@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@zeniv.linux.org.uk>

commit 5aa1437d2d9a068c0334bd7c9dafa8ec4f97f13b upstream.

open file, unlink it, then use ioctl(2) to make it immutable or
append only.  Now close it and watch the blocks *not* freed...

Immutable/append-only checks belong in ->setattr().
Note: the bug is old and backport to anything prior to 737f2e93b972
("ext2: convert to use the new truncate convention") will need
these checks lifted into ext2_setattr().

Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ext2/inode.c |   10 ----------
 1 file changed, 10 deletions(-)

--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1261,21 +1261,11 @@ do_indirects:
 
 static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
 {
-	/*
-	 * XXX: it seems like a bug here that we don't allow
-	 * IS_APPEND inode to have blocks-past-i_size trimmed off.
-	 * review and fix this.
-	 *
-	 * Also would be nice to be able to handle IO errors and such,
-	 * but that's probably too much to ask.
-	 */
 	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
 	    S_ISLNK(inode->i_mode)))
 		return;
 	if (ext2_inode_is_fast_symlink(inode))
 		return;
-	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
-		return;
 
 	dax_sem_down_write(EXT2_I(inode));
 	__ext2_truncate_blocks(inode, offset);