CVE-2024-56581

/// Technical description

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

btrfs: ref-verify: fix use-after-free after invalid ref action

At btrfs_ref_tree_mod() after we successfully inserted the new ref entry

(local variable 'ref') into the respective block entry's rbtree (local

variable 'be'), if we find an unexpected action of BTRFS_DROP_DELAYED_REF,

we error out and free the ref entry without removing it from the block

entry's rbtree. Then in the error path of btrfs_ref_tree_mod() we call

btrfs_free_ref_cache(), which iterates over all block entries and then

calls free_block_entry() for each one, and there we will trigger a

use-after-free when we are called against the block entry to which we

added the freed ref entry to its rbtree, since the rbtree still points

to the block entry, as we didn't remove it from the rbtree before freeing

it in the error path at btrfs_ref_tree_mod(). Fix this by removing the

new ref entry from the rbtree before freeing it.

Syzbot report this with the foll

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References