+++ /dev/null
-From 0d06863f903ac5f4f6efb0273079d27de3e53a28 Mon Sep 17 00:00:00 2001
-From: Theodore Ts'o <tytso@mit.edu>
-Date: Tue, 14 Feb 2017 11:31:15 -0500
-Subject: ext4: don't BUG when truncating encrypted inodes on the orphan list
-
-From: Theodore Ts'o <tytso@mit.edu>
-
-commit 0d06863f903ac5f4f6efb0273079d27de3e53a28 upstream.
-
-Fix a BUG when the kernel tries to mount a file system constructed as
-follows:
-
-echo foo > foo.txt
-mke2fs -Fq -t ext4 -O encrypt foo.img 100
-debugfs -w foo.img << EOF
-write foo.txt a
-set_inode_field a i_flags 0x80800
-set_super_value s_last_orphan 12
-quit
-EOF
-
-root@kvm-xfstests:~# mount -o loop foo.img /mnt
-[ 160.238770] ------------[ cut here ]------------
-[ 160.240106] kernel BUG at /usr/projects/linux/ext4/fs/ext4/inode.c:3874!
-[ 160.240106] invalid opcode: 0000 [#1] SMP
-[ 160.240106] Modules linked in:
-[ 160.240106] CPU: 0 PID: 2547 Comm: mount Tainted: G W 4.10.0-rc3-00034-gcdd33b941b67 #227
-[ 160.240106] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1 04/01/2014
-[ 160.240106] task: f4518000 task.stack: f47b6000
-[ 160.240106] EIP: ext4_block_zero_page_range+0x1a7/0x2b4
-[ 160.240106] EFLAGS: 00010246 CPU: 0
-[ 160.240106] EAX: 00000001 EBX: f7be4b50 ECX: f47b7dc0 EDX: 00000007
-[ 160.240106] ESI: f43b05a8 EDI: f43babec EBP: f47b7dd0 ESP: f47b7dac
-[ 160.240106] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
-[ 160.240106] CR0: 80050033 CR2: bfd85b08 CR3: 34a00680 CR4: 000006f0
-[ 160.240106] Call Trace:
-[ 160.240106] ext4_truncate+0x1e9/0x3e5
-[ 160.240106] ext4_fill_super+0x286f/0x2b1e
-[ 160.240106] ? set_blocksize+0x2e/0x7e
-[ 160.240106] mount_bdev+0x114/0x15f
-[ 160.240106] ext4_mount+0x15/0x17
-[ 160.240106] ? ext4_calculate_overhead+0x39d/0x39d
-[ 160.240106] mount_fs+0x58/0x115
-[ 160.240106] vfs_kern_mount+0x4b/0xae
-[ 160.240106] do_mount+0x671/0x8c3
-[ 160.240106] ? _copy_from_user+0x70/0x83
-[ 160.240106] ? strndup_user+0x31/0x46
-[ 160.240106] SyS_mount+0x57/0x7b
-[ 160.240106] do_int80_syscall_32+0x4f/0x61
-[ 160.240106] entry_INT80_32+0x2f/0x2f
-[ 160.240106] EIP: 0xb76b919e
-[ 160.240106] EFLAGS: 00000246 CPU: 0
-[ 160.240106] EAX: ffffffda EBX: 08053838 ECX: 08052188 EDX: 080537e8
-[ 160.240106] ESI: c0ed0000 EDI: 00000000 EBP: 080537e8 ESP: bfa13660
-[ 160.240106] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b
-[ 160.240106] Code: 59 8b 00 a8 01 0f 84 09 01 00 00 8b 07 66 25 00 f0 66 3d 00 80 75 61 89 f8 e8 3e e2 ff ff 84 c0 74 56 83 bf 48 02 00 00 00 75 02 <0f> 0b 81 7d e8 00 10 00 00 74 02 0f 0b 8b 43 04 8b 53 08 31 c9
-[ 160.240106] EIP: ext4_block_zero_page_range+0x1a7/0x2b4 SS:ESP: 0068:f47b7dac
-[ 160.317241] ---[ end trace d6a773a375c810a5 ]---
-
-The problem is that when the kernel tries to truncate an inode in
-ext4_truncate(), it tries to clear any on-disk data beyond i_size.
-Without the encryption key, it can't do that, and so it triggers a
-BUG.
-
-E2fsck does *not* provide this service, and in practice most file
-systems have their orphan list processed by e2fsck, so to avoid
-crashing, this patch skips this step if we don't have access to the
-encryption key (which is the case when processing the orphan list; in
-all other cases, we will have the encryption key, or the kernel
-wouldn't have allowed the file to be opened).
-
-An open question is whether the fact that e2fsck isn't clearing the
-bytes beyond i_size causing problems --- and if we've lived with it
-not doing it for so long, can we drop this from the kernel replay of
-the orphan list in all cases (not just when we don't have the key for
-encrypted inodes).
-
-Addresses-Google-Bug: #35209576
-
-Signed-off-by: Theodore Ts'o <tytso@mit.edu>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
----
- fs/ext4/inode.c | 4 ++++
- 1 file changed, 4 insertions(+)
-
---- a/fs/ext4/inode.c
-+++ b/fs/ext4/inode.c
-@@ -3363,6 +3363,10 @@ static int ext4_block_truncate_page(hand
- unsigned blocksize;
- struct inode *inode = mapping->host;
-
-+ /* If we are processing an encrypted inode during orphan list handling */
-+ if (ext4_encrypted_inode(inode) && !fscrypt_has_encryption_key(inode))
-+ return 0;
-+
- blocksize = inode->i_sb->s_blocksize;
- length = blocksize - (offset & (blocksize - 1));
-