netdev - Re: [PATCH] eexpress: Read buffer overflow

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Date:	Wed, 29 Jul 2009 14:15:33 +0200
From:	Roel Kluin <roel.kluin@...il.com>
To:	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org, akpm@...ux-foundation.org
Subject: Re: [PATCH] eexpress: Read buffer overflow

start_code is 69 words, but the code always writes a multiple of 16 words,
so the last 11 words written are outside the array.

Signed-off-by: Roel Kluin <roel.kluin@...il.com>
---
Found with Parfait, http://research.sun.com/projects/parfait/

> You've murdered this code, it's even more obfuscated now than it was
> previously. 

Was it really that much worse? I though it was more clean. I did test
it to make sure that the semantics were the same.

> Just add the necessary limit tests, and nothing more, so it's
> possible to actually understand your patch.  If it's more than
> a 3 line patch, I'm not even going to review it.

3 lines it is, although scripts/checkpatch.pl doesn't like it.

Signed-off-by: Roel Kluin <roel.kluin@...il.com>
---
Found with Parfait, http://research.sun.com/projects/parfait/

3 lines it is, but scripts/checkpatch.pl doesn't like it.

diff --git a/drivers/net/eexpress.c b/drivers/net/eexpress.c
index 1686dca..7b40014 100644
--- a/drivers/net/eexpress.c
+++ b/drivers/net/eexpress.c
@@ -1474,13 +1474,13 @@ static void eexp_hw_init586(struct net_device *dev)
 	outw(0x0000, ioaddr + 0x800c);
 	outw(0x0000, ioaddr + 0x800e);
 
-	for (i = 0; i < (sizeof(start_code)); i+=32) {
+	for (i = 0; i < ARRAY_SIZE(start_code); i+=32) {
 		int j;
 		outw(i, ioaddr + SM_PTR);
-		for (j = 0; j < 16; j+=2)
+		for (j = 0; j < 16 && (i+j)/2 < ARRAY_SIZE(start_code); j+=2)
 			outw(start_code[(i+j)/2],
 			     ioaddr+0x4000+j);
-		for (j = 0; j < 16; j+=2)
+		for (j = 0; j < 16 && (i+j+16)/2 < ARRAY_SIZE(start_code); j+=2)
 			outw(start_code[(i+j+16)/2],
 			     ioaddr+0x8000+j);
 	}
--
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