From: Rakesh Pandit <rakesh@xxxxxxxxxx> Subject: 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 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@xxxxxxxxxxxxxxxxxxx Signed-off-by: Rakesh Pandit <rakesh@xxxxxxxxxx> Acked-by: Tigran Aivazian <aivazian.tigran@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/bfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN fs/bfs/inode.c~bfs-fix-sanity-checks-for-empty-files fs/bfs/inode.c --- a/fs/bfs/inode.c~bfs-fix-sanity-checks-for-empty-files +++ a/fs/bfs/inode.c @@ -419,7 +419,7 @@ static int bfs_fill_super(struct super_b 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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
