netdev - Re: [PATCH] slip: Fix memory leak in slip

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Date:   Wed, 13 Nov 2019 12:08:28 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     jouni.hogander@...kie.com
Cc:     netdev@...r.kernel.org, socketcan@...tkopp.net,
        lukas.bulwahn@...il.com
Subject: Re: [PATCH] slip: Fix memory leak in slip_open error path

From: jouni.hogander@...kie.com
Date: Wed, 13 Nov 2019 13:45:02 +0200

> From: Jouni Hogander <jouni.hogander@...kie.com>
> 
> Driver/net/can/slcan.c is derived from slip.c. Memory leak was detected
> by Syzkaller in slcan. Same issue exists in slip.c and this patch is
> addressing the leak in slip.c.
> 
> Here is the slcan memory leak trace reported by Syzkaller:
...
> Signed-off-by: Jouni Hogander <jouni.hogander@...kie.com>

Applied and queued up for -stable.

Looking at slip_open() while reviewing this patch, it has this test:

	if (!test_bit(SLF_INUSE, &sl->flags)) {
		/* Perform the low-level SLIP initialization. */
		err = sl_alloc_bufs(sl, SL_MTU);
		if (err)
			goto err_free_chan;

which seems bogus, because 'sl' here is always a freshly allocated object
from sl_alloc(), which always provides an all-zeros value on sl->flags
so this test always passes.

It can therefore be removed.