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io_uring/rsrc: disallow multi-source reg buffers

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If two or more mappings go back to back to each other they can be passed
into io_uring to be registered as a single registered buffer. That would
even work if mappings came from different sources, e.g. it's possible to
mix in this way anon pages and pages from shmem or hugetlb. That is not
a problem but it'd rather be less prone if we forbid such mixing.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2023-02-22 14:36:48 +00:00 • committed by Jens Axboe
parent 9a1563d172
commit edd4782696
1 changed files with 8 additions and 5 deletions
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13
io_uring/rsrc.c
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@ -1162,14 +1162,17 @@ struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages)
pret = pin_user_pages(ubuf, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
pages, vmas);
if (pret == nr_pages) {
struct file *file = vmas[0]->vm_file;
/* don't support file backed memory */
for (i = 0; i < nr_pages; i++) {
struct vm_area_struct *vma = vmas[i];
if (vma_is_shmem(vma))
if (vmas[i]->vm_file != file) {
ret = -EINVAL;
break;
}
if (!file)
continue;
if (vma->vm_file &&
!is_file_hugepages(vma->vm_file)) {
if (!vma_is_shmem(vmas[i]) && !is_file_hugepages(file)) {
ret = -EOPNOTSUPP;
break;
}