Fix multiple soundness issues #103
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DemiMarie
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@DemiMarie can you please rebase and fix the clippy errors? |
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vfio_syscall::map_dma() accepts a u64 and tells the Linux kernel to make the corresponding address accessible for DMA by a device. Therefore, passing bad u64 values can result in memory corruption or disclosure. Change the u64 argument to a pointer to avoid confusion. To reflect that the caller must uphold invariants to prevent undefined behavior, mark the API as unsafe. I found this through a review of Cloud Hypervisor [1]. Some of its internal APIs took a host took a host address cast to u64 as an argument and accessed that address. In one case, the u64 was passed directly to vfio_syscall::map_dma(). [1]: cloud-hypervisor/cloud-hypervisor#7129 Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
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jinankjain
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Sep 26, 2025
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Summary of the PR
vfio_syscall::map_dma causes the kernel to make an arbitrary address
accessible for DMA by a device the guest typically controls. This is
unsafe, as it can change memory that Rust assumes is immutable.
I found this through a review of Cloud Hypervisor, where I saw a
safe function that took a host address cast to u64 as an argument and
accessed that address. It turns out that this function was the source
of the unsoundness.
Requirements
Before submitting your PR, please make sure you addressed the following
requirements:
git commit -s), and the commit message has max 60 characters for thesummary and max 75 characters for each description line.
test.
Release" section of CHANGELOG.md (if no such section exists, please create one).
unsafecode is properly documented.