Commit 127c03cd authored Aug 03, 2010 by Dominik Brodowski

pcmcia: avoid buffer overflow in pcmcia_setup_isa_irq



NR_IRQS may be as low as 16, causing a (harmless?) buffer overflow in
pcmcia_setup_isa_irq():

static u8 pcmcia_used_irq[NR_IRQS];

...

		if ((try < 32) && pcmcia_used_irq[irq])
			continue;

This is read-only, so if this address would be non-zero, it would just
mean we would not attempt an IRQ >= NR_IRQS -- which would fail anyway!
And as request_irq() fails for an irq >= NR_IRQS, the setting code path:

			pcmcia_used_irq[irq]++;

is never reached as well.

Reported-by: Christoph Fritz <chf.fritz@googlemail.com>
CC: stable@kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>

parent 0f52e86d

drivers/pcmcia/pcmcia_resource.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -677,7 +677,7 @@ EXPORT_SYMBOL(__pcmcia_request_exclusive_irq);
		#ifdef CONFIG_PCMCIA_PROBE

		/* mask of IRQs already reserved by other cards, we should avoid using them */
		static u8 pcmcia_used_irq[NR_IRQS];
		static u8 pcmcia_used_irq[32];

		static irqreturn_t test_action(int cpl, void *dev_id)
		{
		@@ -700,6 +700,9 @@ static int pcmcia_setup_isa_irq(struct pcmcia_device *p_dev, int type)
		for (try = 0; try < 64; try++) {
		irq = try % 32;

		if (irq > NR_IRQS)
		continue;

		/* marked as available by driver, not blocked by userspace? */
		if (!((mask >> irq) & 1))
		continue;