CVE-2024-27066

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

virtio: packed: fix unmap leak for indirect desc table

When use_dma_api and premapped are true, then the do_unmap is false.

Because the do_unmap is false, vring_unmap_extra_packed is not called by detach_buf_packed.

if (unlikely(vq->do_unmap)) { curr = id; for (i = 0; i < state->num; i++) { vring_unmap_extra_packed(vq, &vq->packed.desc_extra[curr]); curr = vq->packed.desc_extra[curr].next; } }

So the indirect desc table is not unmapped. This causes the unmap leak.

So here, we check vq->use_dma_api instead. Synchronously, dma info is updated based on use_dma_api judgment

This bug does not occur, because no driver use the premapped with indirect.

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/51bacd9d29bf98c3ebc65e4a0477bb86306b4140
• https://git.kernel.org/stable/c/75450ff8c6fe8755bf5b139b238eaf9739cfd64e
• https://git.kernel.org/stable/c/d5c0ed17fea60cca9bc3bf1278b49ba79242bbcd
• https://git.kernel.org/stable/c/e142169aca5546ae6619c39a575cda8105362100
• https://git.kernel.org/stable/c/51bacd9d29bf98c3ebc65e4a0477bb86306b4140
• https://git.kernel.org/stable/c/75450ff8c6fe8755bf5b139b238eaf9739cfd64e
• https://git.kernel.org/stable/c/d5c0ed17fea60cca9bc3bf1278b49ba79242bbcd
• https://git.kernel.org/stable/c/e142169aca5546ae6619c39a575cda8105362100