nilfs2: fix infinite loop in nilfs_mdt_get_block()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix infinite loop in nilfs_mdt_get_block() If the disk image that nilfs2 mounts is corrupted and a virtual block address obtained by block lookup for a metadata file is invalid, nilfs_bmap_lookup_at_level() may return the same internal return code as -ENOENT, meaning the block does not exist in the metadata file. This duplication of return codes confuses nilfs_mdt_get_block(), causing it to read and create a metadata block indefinitely. In particular, if this happens to the inode metadata file, ifile, semaphore i_rwsem can be left held, causing task hangs in lock_mount. Fix this issue by making nilfs_bmap_lookup_at_level() treat virtual block address translation failures with -ENOENT as metadata corruption instead of returning the error code.

References

• https://git.kernel.org/stable/c/cfb0bb4fbd40c1f06da7e9f88c0a2d46155b90c2
• https://git.kernel.org/stable/c/d536f9976bb04e9c84cf80045a9355975e418f41
• https://git.kernel.org/stable/c/fe1cbbcb1a2532ee1654e1ff121be8906d83c6f0
• https://git.kernel.org/stable/c/8a89d36a07afe1ed4564df51fefa2bb556c85412
• https://git.kernel.org/stable/c/8d07d9119642ba43d21f8ba64d51d01931096b20
• https://git.kernel.org/stable/c/25457d07c8146e57d28906c663def033dc425af6
• https://git.kernel.org/stable/c/34c5f17222b50c79848bb03ec8811648813e6a45
• https://git.kernel.org/stable/c/5b29661669cb65b9750a3cf70ed3eaf947b92167
• https://git.kernel.org/stable/c/a6a491c048882e7e424d407d32cba0b52d9ef2bf