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Subject[PATCH] bfs: Fix sanity checks for empty files
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

Signed-off-by: Rakesh Pandit <rakesh@tuxera.com>
---

This was sent three years but maintainer has been unresponsive:
https://marc.info/?l=linux-kernel&m=138980764525250

So sending you Andrew as previous patches to bfs have gone through
your tree. This is tested and reproducible.

fs/bfs/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/bfs/inode.c b/fs/bfs/inode.c
index f2deec0..0d3dc18 100644
--- a/fs/bfs/inode.c
+++ b/fs/bfs/inode.c
@@ -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);
--
2.9.3
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