In an effort to separate intentional arithmetic wrap-around from unexpected wrap-around, we need to refactor places that depend on this kind of math. One of the most common code patterns of this is: VAR + value < VAR Notably, this is considered "undefined behavior" for signed and pointer types, which the kernel works around by using the -fno-strict-overflow option in the build[1] (which used to just be -fwrapv). Regardless, we want to get the kernel source to the position where we can meaningfully instrument arithmetic wrap-around conditions and catch them when they are unexpected, regardless of whether they are signed[2], unsigned[3], or pointer[4] types. Refactor open-coded wrap-around addition test to use add_would_overflow(). This paves the way to enabling the wrap-around sanitizers in the future. Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] Link: https://github.com/KSPP/linux/issues/26 [2] Link: https://github.com/KSPP/linux/issues/27 [3] Link: https://github.com/KSPP/linux/issues/344 [4] Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Cc: linux-pci@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- drivers/pci/pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index d8f11a078924..ebf6d9064a59 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4251,7 +4251,7 @@ int pci_register_io_range(struct fwnode_handle *fwnode, phys_addr_t addr, #ifdef PCI_IOBASE struct logic_pio_hwaddr *range; - if (!size || addr + size < addr) + if (!size || add_would_overflow(addr, size)) return -EINVAL; range = kzalloc(sizeof(*range), GFP_ATOMIC); -- 2.34.1
