CVE-2023-52569

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 nodes 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.

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• https://git.kernel.org/stable/c/2c58c3931ede7cd08cbecf1f1a4acaf0a04a41a9
• https://git.kernel.org/stable/c/d10fd53393cc5de4b9cf1a4b8f9984f0a037aa51
• https://git.kernel.org/stable/c/2c58c3931ede7cd08cbecf1f1a4acaf0a04a41a9
• https://git.kernel.org/stable/c/39c4a9522db0072570d602e9b365119e17fb9f4f
• https://git.kernel.org/stable/c/d10fd53393cc5de4b9cf1a4b8f9984f0a037aa51