CVE-2023-52569: btrfs: remove BUG() after failure to insert delayed dir index item

CVE-2023-52569: btrfs: remove BUG() after failure to insert delayed dir index item

[Greg Kroah-Hartman]

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

btrfs: remove BUG() after failure to insert delayed dir index item

Instead of calling BUG() when we fail to insert a delayed dir index item
into the delayed node's tree, we can just release all the resources we
have allocated/acquired before and return the error to the caller. This is
fine because all existing call chains undo anything they have done before
calling btrfs_insert_delayed_dir_index() or BUG_ON (when creating pending
snapshots in the transaction commit path).

So remove the BUG() call and do proper error handling.

This relates to a syzbot report linked below, but does not fix it because
it only prevents hitting a BUG(), it does not fix the issue where somehow
we attempt to use twice the same index number for different index items.

The Linux kernel CVE team has assigned CVE-2023-52569 to this issue.


Affected and fixed versions
===========================

	Fixed in 6.1.56 with commit 39c4a9522db0
	Fixed in 6.5.6 with commit d10fd53393cc
	Fixed in 6.6 with commit 2c58c3931ede

Please see https://www.kernel.org or a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2023-52569
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/btrfs/delayed-inode.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/39c4a9522db0072570d602e9b365119e17fb9f4f
	https://git.kernel.org/stable/c/d10fd53393cc5de4b9cf1a4b8f9984f0a037aa51
	https://git.kernel.org/stable/c/2c58c3931ede7cd08cbecf1f1a4acaf0a04a41a9