[PATCH] powerpc: Read buffer overflow

[PATCH] powerpc: Read buffer overflow

[Roel Kluin]

Check whether index is within bounds before grabbing the element.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
diff --git a/drivers/macintosh/macio_asic.c b/drivers/macintosh/macio_asic.c
index a0f6838..588a5b0 100644
--- a/drivers/macintosh/macio_asic.c
+++ b/drivers/macintosh/macio_asic.c
@@ -294,10 +294,11 @@ static void macio_setup_interrupts(struct macio_dev *dev)
 	int i = 0, j = 0;
 
 	for (;;) {
-		struct resource *res = &dev->interrupt[j];
+		struct resource *res;
 
 		if (j >= MACIO_DEV_COUNT_IRQS)
 			break;
+		res = &dev->interrupt[j];
 		irq = irq_of_parse_and_map(np, i++);
 		if (irq == NO_IRQ)
 			break;
@@ -321,9 +322,10 @@ static void macio_setup_resources(struct macio_dev *dev,
 	int index;
 
 	for (index = 0; of_address_to_resource(np, index, &r) == 0; index++) {
-		struct resource *res = &dev->resource[index];
+		struct resource *res;
 		if (index >= MACIO_DEV_COUNT_RESOURCES)
 			break;
+		res = &dev->resource[index];
 		*res = r;
 		res->name = dev_name(&dev->ofdev.dev);
 

Re: [PATCH] powerpc: Read buffer overflow

[Paul Mackerras]

Roel Kluin writes:

> Check whether index is within bounds before grabbing the element.

The change seems unnecessary since we only compute the address of the
element before the bounds check, we don't actually access the
element.  I believe that is legal in C.

Paul.

Re: [PATCH] powerpc: Read buffer overflow

[Wolfram Sang]

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On Mon, Aug 03, 2009 at 10:57:17PM +1000, Paul Mackerras wrote:
> Roel Kluin writes:
> 
> > Check whether index is within bounds before grabbing the element.
> 
> The change seems unnecessary since we only compute the address of the
> element before the bounds check, we don't actually access the
> element.  I believe that is legal in C.

I've got this strange feeling of deja vu :)

http://thread.gmane.org/gmane.linux.ports.arm.kernel/63507

(I'd vote for applying it but won't mind if not)

Regards,

   Wolfram

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Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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Re: [PATCH] powerpc: Read buffer overflow

[Segher Boessenkool]

> The change seems unnecessary since we only compute the address of the
> element before the bounds check, we don't actually access the
> element.  I believe that is legal in C.

If you have an array a[N], taking &a[0] .. &a[N] are legal C, everything
else is not.


Segher