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ext4: zero i_disksize when initializing the bootloader inode

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commit f5361da1e60d54ec81346aee8e3d8baf1be0b762 upstream.

If the boot loader inode has never been used before, the
EXT4_IOC_SWAP_BOOT inode will initialize it, including setting the
i_size to 0.  However, if the "never before used" boot loader has a
non-zero i_size, then i_disksize will be non-zero, and the
inconsistency between i_size and i_disksize can trigger a kernel
warning:

 WARNING: CPU: 0 PID: 2580 at fs/ext4/file.c:319
 CPU: 0 PID: 2580 Comm: bb Not tainted 6.3.0-rc1-00004-g703695902cfa
 RIP: 0010:ext4_file_write_iter+0xbc7/0xd10
 Call Trace:
  vfs_write+0x3b1/0x5c0
  ksys_write+0x77/0x160
  __x64_sys_write+0x22/0x30
  do_syscall_64+0x39/0x80

Reproducer:
 1. create corrupted image and mount it:
       mke2fs -t ext4 /tmp/foo.img 200
       debugfs -wR "sif <5> size 25700" /tmp/foo.img
       mount -t ext4 /tmp/foo.img /mnt
       cd /mnt
       echo 123 > file
 2. Run the reproducer program:
       posix_memalign(&buf, 1024, 1024)
       fd = open("file", O_RDWR | O_DIRECT);
       ioctl(fd, EXT4_IOC_SWAP_BOOT);
       write(fd, buf, 1024);

Fix this by setting i_disksize as well as i_size to zero when
initiaizing the boot loader inode.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217159
Cc: stable@kernel.org
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Link: https://lore.kernel.org/r/20230308032643.641113-1-chengzhihao1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Zhihao Cheng 2023-03-08 11:26:43 +08:00 committed by Greg Kroah-Hartman
parent 74d775083e
commit 0d8a6c9a64
1 changed files with 1 additions and 0 deletions
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1
fs/ext4/ioctl.c
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@ -179,6 +179,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
ei_bl->i_flags = 0;
inode_set_iversion(inode_bl, 1);
i_size_write(inode_bl, 0);
EXT4_I(inode_bl)->i_disksize = inode_bl->i_size;
inode_bl->i_mode = S_IFREG;
if (ext4_has_feature_extents(sb)) {
ext4_set_inode_flag(inode_bl, EXT4_INODE_EXTENTS);