Patch "ext4 crypto: fix bugs in ext4_encrypted_zeroout()" has been added to the 4.2-stable tree

Patch "ext4 crypto: fix bugs in ext4_encrypted_zeroout()" has been added to the 4.2-stable tree

[gregkh]

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

    ext4 crypto: fix bugs in ext4_encrypted_zeroout()

to the 4.2-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:
     ext4-crypto-fix-bugs-in-ext4_encrypted_zeroout.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 36086d43f6575c081067de9855786a2fc91df77b Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Sat, 3 Oct 2015 10:49:29 -0400
Subject: ext4 crypto: fix bugs in ext4_encrypted_zeroout()

From: Theodore Ts'o <tytso@mit.edu>

commit 36086d43f6575c081067de9855786a2fc91df77b upstream.

Fix multiple bugs in ext4_encrypted_zeroout(), including one that
could cause us to write an encrypted zero page to the wrong location
on disk, potentially causing data and file system corruption.
Fortunately, this tends to only show up in stress tests, but even with
these fixes, we are seeing some test failures with generic/127 --- but
these are now caused by data failures instead of metadata corruption.

Since ext4_encrypted_zeroout() is only used for some optimizations to
keep the extent tree from being too fragmented, and
ext4_encrypted_zeroout() itself isn't all that optimized from a time
or IOPS perspective, disable the extent tree optimization for
encrypted inodes for now.  This prevents the data corruption issues
reported by generic/127 until we can figure out what's going wrong.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ext4/crypto.c  |   23 +++++++++++++++++++----
 fs/ext4/extents.c |    3 +++
 2 files changed, 22 insertions(+), 4 deletions(-)

--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -410,7 +410,13 @@ int ext4_encrypted_zeroout(struct inode
 	ext4_lblk_t		lblk = ex->ee_block;
 	ext4_fsblk_t		pblk = ext4_ext_pblock(ex);
 	unsigned int		len = ext4_ext_get_actual_len(ex);
-	int			err = 0;
+	int			ret, err = 0;
+
+#if 0
+	ext4_msg(inode->i_sb, KERN_CRIT,
+		 "ext4_encrypted_zeroout ino %lu lblk %u len %u",
+		 (unsigned long) inode->i_ino, lblk, len);
+#endif
 
 	BUG_ON(inode->i_sb->s_blocksize != PAGE_CACHE_SIZE);
 
@@ -436,17 +442,26 @@ int ext4_encrypted_zeroout(struct inode
 			goto errout;
 		}
 		bio->bi_bdev = inode->i_sb->s_bdev;
-		bio->bi_iter.bi_sector = pblk;
-		err = bio_add_page(bio, ciphertext_page,
+		bio->bi_iter.bi_sector =
+			pblk << (inode->i_sb->s_blocksize_bits - 9);
+		ret = bio_add_page(bio, ciphertext_page,
 				   inode->i_sb->s_blocksize, 0);
-		if (err) {
+		if (ret != inode->i_sb->s_blocksize) {
+			/* should never happen! */
+			ext4_msg(inode->i_sb, KERN_ERR,
+				 "bio_add_page failed: %d", ret);
+			WARN_ON(1);
 			bio_put(bio);
+			err = -EIO;
 			goto errout;
 		}
 		err = submit_bio_wait(WRITE, bio);
+		if ((err == 0) && bio->bi_error)
+			err = -EIO;
 		bio_put(bio);
 		if (err)
 			goto errout;
+		lblk++; pblk++;
 	}
 	err = 0;
 errout:
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3558,6 +3558,9 @@ static int ext4_ext_convert_to_initializ
 		max_zeroout = sbi->s_extent_max_zeroout_kb >>
 			(inode->i_sb->s_blocksize_bits - 10);
 
+	if (ext4_encrypted_inode(inode))
+		max_zeroout = 0;
+
 	/* If extent is less than s_max_zeroout_kb, zeroout directly */
 	if (max_zeroout && (ee_len <= max_zeroout)) {
 		err = ext4_ext_zeroout(inode, ex);


Patches currently in stable-queue which might be from tytso@mit.edu are

queue-4.2/ext4-jbd2-ensure-entering-into-panic-after-recording-an-error-in-superblock.patch
queue-4.2/ext4-crypto-replace-some-bug_on-s-with-error-checks.patch
queue-4.2/ext4-crypto-fix-bugs-in-ext4_encrypted_zeroout.patch
queue-4.2/ext4-crypto-fix-memory-leak-in-ext4_bio_write_page.patch