Re: [PATCH][stable] b44 WOL setup: one-bit-off stack corruption kernel panic fix

[Stanislav Brabec <sbrabec@suse.cz>]

Stanislav Brabec wrote:
> 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 on 2006-06-20.

stable@kernel.org may be interested as well. Adding Cc:.

Signed-off-by: Stanislav Brabec <sbrabec@suse.cz>
Cc: stable@kernel.org


diff --git a/drivers/net/b44.c b/drivers/net/b44.c
index 2a91323..4869adb 100644
--- a/drivers/net/b44.c
+++ b/drivers/net/b44.c
@@ -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;



-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
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