Re: [net-next:master 209/235] drivers/net/usb/smsc95xx.c:1134:39-50: ERROR: reference preceded by free on line 1136

Julia,

On Thu, Nov 08, 2012 at 09:08:04AM +0100, Julia Lawall wrote:

It's a false positive because check_warn_return does a return.

Right.

But I wonder if there is a way that we can encourage people not to
do things like that?

Well I suspect the memory leak bug 06a221be0 tries to fix might be
due to check_warn_return() hiding the otherwise very obvious syntax
highlighted 'return' statement.

Thanks,
Fengguang

quoted

TO: Ming Lei <redacted>
CC: netdev@vger.kernel.org


Hi Ming,

FYI, there are coccinelle warnings in

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
head:   f1e0b5b4f1eae56a3192688177f36e2bdf0e01ac
commit: 06a221be022c2cc98a48e0808a4ef0dc8f0b3a34 [209/235] usbnet: smsc95xx: fix memory leak in smsc95xx_suspend
:::::: branch date: 8 hours ago
:::::: commit date: 23 hours ago

+ drivers/net/usb/smsc95xx.c:1134:39-50: ERROR: reference preceded by free on line 1136
drivers/net/usb/smsc95xx.c:1139:8-19: ERROR: reference preceded by free on line 1136

git remote update net-next
git checkout 06a221be022c2cc98a48e0808a4ef0dc8f0b3a34
vim +1134 drivers/net/usb/smsc95xx.c

bbd9f9ee Steve Glendinning 2012-10-26  1128  			offset[filter/4] |= 0x00 << ((filter % 4) * 8);
bbd9f9ee Steve Glendinning 2012-10-26  1129  			crc[filter/2] |= smsc_crc(dev->net->dev_addr, ETH_ALEN, filter);
bbd9f9ee Steve Glendinning 2012-10-26  1130  			filter++;
bbd9f9ee Steve Glendinning 2012-10-26  1131  		}
bbd9f9ee Steve Glendinning 2012-10-26  1132
bbd9f9ee Steve Glendinning 2012-10-26  1133  		for (i = 0; i < (pdata->wuff_filter_count * 4); i++) {
bbd9f9ee Steve Glendinning 2012-10-26 @1134  			ret = smsc95xx_write_reg(dev, WUFF, filter_mask[i]);
06a221be Ming Lei          2012-11-06  1135  			if (ret < 0)
06a221be Ming Lei          2012-11-06 @1136  				kfree(filter_mask);
bbd9f9ee Steve Glendinning 2012-10-26  1137  			check_warn_return(ret, "Error writing WUFF");
bbd9f9ee Steve Glendinning 2012-10-26  1138  		}
06a221be Ming Lei          2012-11-06  1139  		kfree(filter_mask);

:::::: The code at line 1134 was first introduced by commit:
:::::: bbd9f9e smsc95xx: add wol support for more frame types

:::::: TO: Steve Glendinning [off-list ref]
:::::: CC: David S. Miller [off-list ref]

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0-DAY kernel build testing backend         Open Source Technology Center
Fengguang Wu, Yuanhan Liu                              Intel Corporation