[PATCH v2] tty: rocket: Fix possible buffer overwrite on register_PCI

From: Anton Vasilyev
Date: Mon Aug 06 2018 - 10:12:06 EST

If number of isa and pci boards exceed NUM_BOARDS on the path
rp_init()->init_PCI()->register_PCI() then buffer overwrite occurs
in register_PCI() on assign rcktpt_io_addr[i].

The patch adds check on upper bound for index of registered
board in register_PCI.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@xxxxxxxxx>
v2: do not enable device which will not be managed by driver.
Based on Alan's comment.

NOTE: I can't find if there is a call of pci_disable_device(),
corresponding to pci_enable_device() from register_PCI().
drivers/tty/rocket.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/rocket.c b/drivers/tty/rocket.c
index bdd17d2aaafd..f2238dc40426 100644
--- a/drivers/tty/rocket.c
+++ b/drivers/tty/rocket.c
@@ -1881,7 +1881,7 @@ static __init int register_PCI(int i, struct pci_dev *dev)
ByteIO_t UPCIRingInd = 0;

if (!dev || !pci_match_id(rocket_pci_ids, dev) ||
- pci_enable_device(dev))
+ i >= NUM_BOARDS || pci_enable_device(dev))
return 0;

rcktpt_io_addr[i] = pci_resource_start(dev, 0);