"resource->end" needs to always be equal to "resource->start + size - 1". The previous version of the function did not perform the "- 1" in case of an empty resource.

Also make sure to allow an empty resource at address 0.

Reported-by: Basharath Hussain Khaja basharath@couthit.com Closes: https://lore.kernel.org/lkml/20250108140414.13530-1-basharath@couthit.com/ Fixes: 1a52a094c2f0 ("of: address: Unify resource bounds overflow checking") Cc: stable@vger.kernel.org Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de --- drivers/of/address.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c index 8770004d9b085f1ff40f693d695d284a6ef3dfde..5c0663066a7f3816a05077f99124ca25e3c152d7 100644 --- a/drivers/of/address.c +++ b/drivers/of/address.c @@ -200,17 +200,15 @@ static u64 of_bus_pci_map(__be32 *addr, const __be32 *range, int na, int ns,

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 && check_add_overflow(end, size - 1, &end)) - return -EOVERFLOW; - if (overflows_type(end, r->end)) - return -EOVERFLOW;

r->start = start; - r->end = end; + + if (!size) + r->end = wrapping_sub(typeof(r->end), r->start, 1); + else if (size && check_add_overflow(r->start, size - 1, &r->end)) + return -EOVERFLOW;

return 0; }