nilfs2: handle inconsistent state in nilfs_btnode_create_block()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: handle inconsistent state in nilfs_btnode_create_block() Syzbot reported that a buffer state inconsistency was detected in nilfs_btnode_create_block(), triggering a kernel bug. It is not appropriate to treat this inconsistency as a bug; it can occur if the argument block address (the buffer index of the newly created block) is a virtual block number and has been reallocated due to corruption of the bitmap used to manage its allocation state. So, modify nilfs_btnode_create_block() and its callers to treat it as a possible filesystem error, rather than triggering a kernel bug.

References

• https://git.kernel.org/stable/c/19cce46238ffe3546e44b9c74057103ff8b24c62
• https://git.kernel.org/stable/c/02b87e6334a38c65eef49848d3f1ac422f0b2a44
• https://git.kernel.org/stable/c/5f0a6800b8aec1b453c7fe4c44fcaac5ffe9d52e
• https://git.kernel.org/stable/c/e34191cce3ee63dfa5fb241904aaf2a042d5b6d8
• https://git.kernel.org/stable/c/012be828a118bf496e666ef1fc47fc0e7358ada2
• https://git.kernel.org/stable/c/be56dfc9be0604291267c07b0e27a69a6bda4899
• https://git.kernel.org/stable/c/366c3f688dd0288cbe38af1d3a886b5c62372e4a
• https://git.kernel.org/stable/c/4811f7af6090e8f5a398fbdd766f903ef6c0d787