[PATCH] serial: 8250_pci1xxxx: Annotate struct pci1xxxx_8250 with __counted_by

[Kees Cook]

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct pci1xxxx_8250.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Kumaravel Thiagarajan <kumaravel.thiagarajan@xxxxxxxxxxxxx>
Cc: Tharun Kumar P <tharunkumar.pasumarthi@xxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Slaby <jirislaby@xxxxxxxxxx>
Cc: linux-serial@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_pci1xxxx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c
index a3b25779d921..0da9847f3e91 100644
--- a/drivers/tty/serial/8250/8250_pci1xxxx.c
+++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
@@ -107,7 +107,7 @@ static const int logical_to_physical_port_idx[][MAX_PORTS] = {
 struct pci1xxxx_8250 {
 	unsigned int nr;
 	void __iomem *membase;
-	int line[];
+	int line[] __counted_by(nr);
 };
 
 static int pci1xxxx_get_num_ports(struct pci_dev *dev)
-- 
2.34.1