CVE-2024-44964

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

idpf: fix memory leaks and crashes while performing a soft reset

The second tagged commit introduced a UAF, as it removed restoring q_vector->vport pointers after reinitializating the structures. This is due to that all queue allocation functions are performed here with the new temporary vport structure and those functions rewrite the backpointers to the vport. Then, this new struct is freed and the pointers start leading to nowhere.

But generally speaking, the current logic is very fragile. It claims to be more reliable when the system is low on memory, but in fact, it consumes two times more memory as at the moment of running this function, there are two vports allocated with their queues and vectors. Moreover, it claims to prevent the driver from running into bad state, but in fact, any error during the rebuild leaves the old vport in the partially allocated state. Finally, if the interface is down when the function is called, it always allocates a new queue set, but when the user decides to enable the interface later on, vport_open() allocates them once again, IOW theres a clear memory leak here.

Just dont allocate a new queue set when performing a reset, that solves crashes and memory leaks. Readd the old queue number and reopen the interface on rollback - that solves limbo states when the device is left disabled and/or without HW queues enabled.

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/6b289f8d91537ec1e4f9c7b38b31b90d93b1419b
• https://git.kernel.org/stable/c/f01032a2ca099ec8d619aaa916c3762aa62495df