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4d70986002
iommufd_hwpt_invalidate() takes a user-controlled entry_num and entry_len,
each bounded only by U32_MAX. An entry_len beyond the kernel's struct size
makes the copy helper verify the extra bytes are zero, scanning that excess
in one uninterruptible pass; a multi-gigabyte value over zeroed user memory
trips the soft-lockup watchdog.
A large entry_num is the other half, driving the backend invalidation loop
with no reschedule. The VT-d nested handler, for one, copies each entry and
flushes caches per iteration, pinning the CPU on a non-preemptible kernel.
Cap both in the ioctl. entry_len is held under PAGE_SIZE, above any request
struct, and entry_num under 1 << 19, the order of a hardware invalidation
queue and well beyond any real batch, bounding the per-call loop length.
Fixes:
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||
|---|---|---|
| .. | ||
| device.c | ||
| double_span.h | ||
| driver.c | ||
| eventq.c | ||
| hw_pagetable.c | ||
| io_pagetable.c | ||
| io_pagetable.h | ||
| ioas.c | ||
| iommufd_private.h | ||
| iommufd_test.h | ||
| iova_bitmap.c | ||
| Kconfig | ||
| main.c | ||
| Makefile | ||
| pages.c | ||
| selftest.c | ||
| vfio_compat.c | ||
| viommu.c | ||