Commit e0188829 authored Dec 08, 2009 by Stanislav Brabec Committed by David S. Miller Dec 08, 2009

b44 WOL setup: one-bit-off stack corruption kernel panic fix



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@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 77722b17

drivers/net/b44.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -1505,8 +1505,7 @@ static int b44_magic_pattern(u8 macaddr, u8 ppattern, u8 *pmask, int offset)
		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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