linux-cve-announce - CVE-2024-44963: btrfs: do not BUG_ON() when freeing tree block after error

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Message-ID: <2024090414-CVE-2024-44963-2e6d@gregkh>
Date: Wed,  4 Sep 2024 20:36:23 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-44963: btrfs: do not BUG_ON() when freeing tree block after error

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

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

btrfs: do not BUG_ON() when freeing tree block after error

When freeing a tree block, at btrfs_free_tree_block(), if we fail to
create a delayed reference we don't deal with the error and just do a
BUG_ON(). The error most likely to happen is -ENOMEM, and we have a
comment mentioning that only -ENOMEM can happen, but that is not true,
because in case qgroups are enabled any error returned from
btrfs_qgroup_trace_extent_post() (can be -EUCLEAN or anything returned
from btrfs_search_slot() for example) can be propagated back to
btrfs_free_tree_block().

So stop doing a BUG_ON() and return the error to the callers and make
them abort the transaction to prevent leaking space. Syzbot was
triggering this, likely due to memory allocation failure injection.

The Linux kernel CVE team has assigned CVE-2024-44963 to this issue.

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

	Fixed in 6.10.5 with commit 98251cd60b4d
	Fixed in 6.11-rc1 with commit bb3868033a4c

Please see https://www.kernel.org for 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-2024-44963
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/ctree.c
	fs/btrfs/extent-tree.c
	fs/btrfs/extent-tree.h
	fs/btrfs/free-space-tree.c
	fs/btrfs/ioctl.c
	fs/btrfs/qgroup.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/98251cd60b4d702a8a81de442ab621e83a3fb24f
	https://git.kernel.org/stable/c/bb3868033a4cccff7be57e9145f2117cbdc91c11