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bfs: fix sanity checks for empty files

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Mount fails if file system image has empty files because of sanity check
while reading superblock.  For empty files disk offset to end of file
(i_eoffset) is cpu_to_le32(-1).  Sanity check comparison, which compares
disk offset with file system size isn't valid for this value and hence
is ignored with this patch.

Steps to reproduce:

  $  dd if=/dev/zero of=bfs-image count=204800
  $  mkfs.bfs bfs-image
  $  mkdir bfs-mount-point
  $  sudo mount -t bfs -o loop bfs-image bfs-mount-point/
  $  cd bfs-mount-point/
  $  sudo touch a
  $  cd ..
  $  sudo umount bfs-mount-point/
  $  sudo mount -t bfs -o loop bfs-image bfs-mount-point/
  mount: /dev/loop0: can't read superblock

  $  dmesg
  [25526.689580] BFS-fs: bfs_fill_super(): Inode 0x00000003 corrupted

Tigran said:
 "If you had created the filesystem with the proper mkfs under SCO
  UnixWare 7 you (probably) wouldn't encounter this issue. But since
  commercial Unix-es are now part of history and the only proper way is
  the Linux mkfs.bfs utility, your patch is fine"

Link: http://lkml.kernel.org/r/20170505201625.GA3097@hercules.tuxera.com
Signed-off-by: Rakesh Pandit <rakesh@tuxera.com>
Acked-by: Tigran Aivazian <aivazian.tigran@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rakesh Pandit 2017-07-12 14:34:07 -07:00 committed by Linus Torvalds
parent ee7998c50c
commit 5f9f48f5b3
1 changed files with 1 additions and 1 deletions
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2
fs/bfs/inode.c
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@ -419,7 +419,7 @@ static int bfs_fill_super(struct super_block *s, void *data, int silent)
if (i_sblock > info->si_blocks ||
i_eblock > info->si_blocks ||
i_sblock > i_eblock ||
i_eoff > s_size ||
(i_eoff != le32_to_cpu(-1) && i_eoff > s_size) ||
i_sblock * BFS_BSIZE > i_eoff) {
printf("Inode 0x%08x corrupted\n", i);