selftests: dmabuf-heaps: add fd-leak-on-EFAULT regression test

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Add a test case that verifies no file descriptor is leaked when
DMA_HEAP_IOCTL_ALLOC succeeds internally but copy_to_user() fails
to deliver the fd number back to userspace.

The failure is triggered by placing the ioctl argument in a private
anonymous page and flipping it to PROT_READ (via mprotect) between
the kernel's copy_from_user() and copy_to_user() calls.  With the
buggy kernel the ioctl returns -EFAULT but leaves an extra open fd
in the process's fd table; with the fixed kernel the fd count is
unchanged.

This serves as a regression test for:
  "dma-buf: dma-heap: don't publish fd before copy_to_user() succeeds"

Suggested-by: Sumit Semwal <sumit.semwal@linaro.org>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Baineng Shou <shoubaineng@gmail.com>
Link: https://lore.kernel.org/r/20260817050457.1005285-5-shoubaineng@gmail.com
Signed-off-by: Christian König <christian.koenig@amd.com>

...

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Baineng Shou 2026-08-17 13:04:57 +08:00 • committed by Christian König

parent 3e164bf592

commit 8985cbc927

1 changed files with 112 additions and 1 deletions

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tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c

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