Re: [PATCH v2 1/3] PCI: Relaxed tail alignment should never increase min_align

21 Aug 2025


      On Thu, 21 Aug 2025, Markus Elfring wrote:
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Ensure min_align is not increased by the relaxed tail alignment.
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+++ b/drivers/pci/setup-bus.c
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@@ -1261,8 +1263,9 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
   	if (bus->self && size1 &&
   	    !pbus_upstream_space_available(bus, mask | IORESOURCE_PREFETCH, type,
   					   size1, add_align)) {

	min_align = 1ULL << (max_order + __ffs(SZ_1M));


	min_align = max(min_align, win_align);




	relaxed_align = 1ULL << (max_order + __ffs(SZ_1M));


	relaxed_align = max(min_align, win_align);



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I wonder why a variable content would be overwritten here
without using the previous value.
https://cwe.mitre.org/data/definitions/563.html
Hi Markus,
This looks a very good catch. I think it too should have been:
relaxed_align = max(relaxed_align, win_align);
...like in the other case.
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 i.

    