CVE-2024-41078

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

btrfs: qgroup: fix quota root leak after quota disable failure

If during the quota disable we fail when cleaning the quota tree or when deleting the root from the root tree, we jump to the out label without ever dropping the reference on the quota root, resulting in a leak of the root since fs_info->quota_root is no longer pointing to the root (we have set it to NULL just before those steps).

Fix this by always doing a btrfs_put_root() call under the out label. This is a problem that exists since qgroups were first added in 2012 by commit bed92eae26cc (Btrfs: qgroup implementation and prototypes), but back then we missed a kfree on the quota root and free_extent_buffer() calls on its root and commit root nodes, since back then roots were not yet reference counted.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/5ef3961682e5310f2221bae99bcf9f5d0f4b0d51
• https://git.kernel.org/stable/c/7dd6a5b96157a21245566b21fd58276a214357ff
• https://git.kernel.org/stable/c/8a69529f22590b67bb018de9acbcf94abc8603cf
• https://git.kernel.org/stable/c/94818bdb00ef34a996a06aa63d11f591074cb757
• https://git.kernel.org/stable/c/a7e4c6a3031c74078dba7fa36239d0f4fe476c53
• https://git.kernel.org/stable/c/f88aeff5a173e8ba3133314eb4b964236ef3589d
• https://git.kernel.org/stable/c/5ef3961682e5310f2221bae99bcf9f5d0f4b0d51
• https://git.kernel.org/stable/c/7dd6a5b96157a21245566b21fd58276a214357ff
• https://git.kernel.org/stable/c/8a69529f22590b67bb018de9acbcf94abc8603cf
• https://git.kernel.org/stable/c/94818bdb00ef34a996a06aa63d11f591074cb757
• https://git.kernel.org/stable/c/a7e4c6a3031c74078dba7fa36239d0f4fe476c53
• https://git.kernel.org/stable/c/f88aeff5a173e8ba3133314eb4b964236ef3589d
• https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html