[48/90] b44 WOL setup: one-bit-off stack corruption kernel panic fix

From: Greg KH
Date: Wed Dec 16 2009 - 20:36:24 EST

2.6.31-stable review patch. If anyone has any objections, please let us know.


From: Stanislav Brabec <sbrabec@xxxxxxx>

[ Upstream commit: e0188829cb724e7d12a2d4e343b368ff1d6e1471 ]

About 50% of shutdowns of b44 Ethernet adapter ends by kernel panic
with kernels compiled with stack-protector.

Checking b44_magic_pattern() return values, one call of
b44_magic_pattern() returns 127. It means, that set_bit(128, pmask)
was called on line 1509. It means that bit 0 of 17th byte of pmask was
overwritten. But pmask has only 16 bytes. Stack corruption happens.

It seems that set_bit() on line 1509 always writes one bit off.

The fix does not only solve the stack corruption, but also makes Wake
On LAN working on my onboard B44 on Asus A7V-333X mainboard.

It seems that this problem affects all kernel versions since commit
725ad800 ([PATCH] b44: add wol for old nic) on 2006-06-20.

Signed-off-by: Stanislav Brabec <sbrabec@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
drivers/net/b44.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/net/b44.c
+++ b/drivers/net/b44.c
@@ -1505,8 +1505,7 @@ static int b44_magic_pattern(u8 *macaddr
for (k = 0; k< ethaddr_bytes; k++) {
ppattern[offset + magicsync +
(j * ETH_ALEN) + k] = macaddr[k];
- len++;
- set_bit(len, (unsigned long *) pmask);
+ set_bit(len++, (unsigned long *) pmask);
return len - 1;

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