swiotlb: Enforce page alignment in swiotlb_alloc()

When allocating pages from a restricted DMA pool in swiotlb_alloc(),
the buffer address is blindly converted to a 'struct page *' that is
returned to the caller. In the unlikely event of an allocation bug,
page-unaligned addresses are not detected and slots can silently be
double-allocated.

Add a simple check of the buffer alignment in swiotlb_alloc() to make
debugging a little easier if something has gone wonky.

Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Petr Tesarik <petr.tesarik1@huawei-partners.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Will Deacon 2024-03-08 15:28:25 +00:00 committed by Christoph Hellwig
parent 04867a7a33
commit 823353b7cf

View File

@ -1689,6 +1689,12 @@ struct page *swiotlb_alloc(struct device *dev, size_t size)
return NULL;
tlb_addr = slot_addr(pool->start, index);
if (unlikely(!PAGE_ALIGNED(tlb_addr))) {
dev_WARN_ONCE(dev, 1, "Cannot allocate pages from non page-aligned swiotlb addr 0x%pa.\n",
&tlb_addr);
swiotlb_release_slots(dev, tlb_addr);
return NULL;
}
return pfn_to_page(PFN_DOWN(tlb_addr));
}