[PATCH 4.18 073/158] tty: rocket: Fix possible buffer overwrite on register_PCI

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Anton Vasilyev <vasilyev@xxxxxxxxx>

[ Upstream commit 0419056ec8fd01ddf5460d2dba0491aad22657dd ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/tty/rocket.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/tty/rocket.c
+++ b/drivers/tty/rocket.c
@@ -1881,7 +1881,7 @@ static __init int register_PCI(int i, st
 	ByteIO_t UPCIRingInd = 0;
 
 	if (!dev || !pci_match_id(rocket_pci_ids, dev) ||
-	    pci_enable_device(dev))
+	    pci_enable_device(dev) || i >= NUM_BOARDS)
 		return 0;
 
 	rcktpt_io_addr[i] = pci_resource_start(dev, 0);