Rob Herring [off-list ref] writes:

On Fri, Sep 13, 2024 at 8:15 AM Michael Ellerman [off-list ref] wrote:

quoted

Thomas Weißschuh [off-list ref] writes:

quoted

The members "start" and "end" of struct resource are of type
"resource_size_t" which can be 32bit wide.
Values read from OF however are always 64bit wide.

Refactor the diff overflow checks into a helper function.
Also extend the checks to validate each calculation step.

Signed-off-by: Thomas Weißschuh <redacted>
---
 drivers/of/address.c | 45 ++++++++++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 19 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 7e59283a4472..df854bb427ce 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c

@@ -198,6 +198,25 @@ static u64 of_bus_pci_map(__be32 *addr, const __be32 *range, int na, int ns,

 #endif /* CONFIG_PCI */

+static int __of_address_resource_bounds(struct resource *r, u64 start, u64 size)
+{
+     u64 end = start;
+
+     if (overflows_type(start, r->start))
+             return -EOVERFLOW;
+     if (size == 0)
+             return -EOVERFLOW;
+     if (check_add_overflow(end, size - 1, &end))
+             return -EOVERFLOW;
+     if (overflows_type(end, r->end))
+             return -EOVERFLOW;

This breaks PCI on powerpc qemu. Part of the PCI probe reads a resource
that's zero sized, which used to succeed but now fails due to the size
check above.

The diff below fixes it for me.

I fixed it up with your change.

Thanks.

cheers