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z_impl_vregion_create_map() wrote the region start and size to the caller's buffers and then read them back to build the memory partition. As a system call these buffers are user memory, so another thread could change them in between and get arbitrary memory mapped into the LL domain. Read the requested size once, build the partitions from kernel locals and write the results only at the end. Also set vr->domain after the first partition is added, so a failure adding the second one unmaps the first. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
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November 3, 2026 17:41
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🟡 Changes recommended
Concurrent user-space vregion_put() calls can consume each other’s validator references, freeing the region before another release accesses it and causing a kernel use-after-free.
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What changed in this PR
This PR hardens virtual-region syscall validation by checking handles against a kernel-maintained list and taking temporary references during syscall execution.
Changes:
- Adds live-region tracking and reference-taking validation.
- Updates syscall wrappers and the validation API.
- Uses local mapping parameters and improves cleanup after partial mapping failures.
| File | Description |
|---|---|
zephyr/syscall/vregion.c |
Uses reference-taking validation in syscall wrappers. |
zephyr/lib/vregion.c |
Tracks live regions, updates lifetime handling, and hardens mapping setup. |
src/include/sof/lib/vregion.h |
Renames the validator and documents its reference ownership contract. |
Review effort: Balanced
Comment on lines
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| z_impl_vregion_put(vr); | ||
| return z_impl_vregion_put(vr); |
PR 11396: test resultsRun date: 2026-11-04 12:51 UTC Tested commit: 7740914ac5d80a6f3f024a46bb93b392c965d064
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vregion_verify() accepted any pointer to memory the caller cannot read, as long as the two words at its start looked like a user-writable range. A forged handle let the kernel lock, count, initialize and free kernel memory of the caller's choice. A concurrent vregion_put() could also free a vregion between validation and use. Keep live vregions in a kernel-only list. vregion_verify_pin() looks the handle up and pins it under the list lock, and the validators unpin it after the call. Pins are counted separately from references, so a vregion_put() call of another thread can not consume them, and a vregion is destroyed only when both its references and its pins are gone. vregion_put() removes the last reference and the list entry atomically with respect to lookups. The vregion_get() and vregion_put() validators take or drop the caller's reference under the lock, and a put without a reference left is rejected instead of underflowing the count. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
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A few fixes to vregion syscall validation.