linux-kernel - [PATCH v2] tty: rocket: Fix possible buffer overwrite on register

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Message-Id: <20180806141057.7105-1-vasilyev@ispras.ru>
Date:   Mon,  6 Aug 2018 17:10:57 +0300
From:   Anton Vasilyev <vasilyev@...ras.ru>
To:     Alan Cox <gnomes@...rguk.ukuu.org.uk>
Cc:     Anton Vasilyev <vasilyev@...ras.ru>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org
Subject: [PATCH v2] tty: rocket: Fix possible buffer overwrite on register_PCI

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@...ras.ru>
---
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);
-- 
2.18.0