From: Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
To: Joe Perches <joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org>
Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
b.a.t.m.a.n-ZwoEplunGu2X36UT3dwllkB+6BGkLq7r@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Antonio Quartulli
<antonio-x4xJYDvStAgysxA8WJXlww@public.gmane.org>,
"David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>,
Marek Lindner
<mareklindner-rVWd3aGhH2z5bpWLKbzFeg@public.gmane.org>
Subject: Re: [PATCH -next 2/3] batman-adv: Use seq_overflow
Date: Wed, 11 Dec 2013 07:55:26 +0000 [thread overview]
Message-ID: <20131211075526.GR10323@ZenIV.linux.org.uk> (raw)
In-Reply-To: <e7104b35287b1e1ec456734c1b5e1aa98dac99f8.1386738050.git.joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org>
On Tue, Dec 10, 2013 at 09:12:43PM -0800, Joe Perches wrote:
> diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
> index 2449afa..dfa5d2d 100644
> --- a/net/batman-adv/gateway_client.c
> +++ b/net/batman-adv/gateway_client.c
> @@ -517,29 +517,28 @@ static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
> {
> struct batadv_gw_node *curr_gw;
> struct batadv_neigh_node *router;
> - int ret = -1;
>
> router = batadv_orig_node_get_router(gw_node->orig_node);
> if (!router)
> - goto out;
> + return -1;
This (as well as the original) means "fail read(2) with -EINVAL", which
might or might not be correct behaviour.
> curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
>
> - ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n",
> - (curr_gw == gw_node ? "=>" : " "),
> - gw_node->orig_node->orig,
> - router->bat_iv.tq_avg, router->addr,
> - router->if_incoming->net_dev->name,
> - gw_node->bandwidth_down / 10,
> - gw_node->bandwidth_down % 10,
> - gw_node->bandwidth_up / 10,
> - gw_node->bandwidth_up % 10);
> + seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n",
> + (curr_gw == gw_node ? "=>" : " "),
> + gw_node->orig_node->orig,
> + router->bat_iv.tq_avg, router->addr,
> + router->if_incoming->net_dev->name,
> + gw_node->bandwidth_down / 10,
> + gw_node->bandwidth_down % 10,
> + gw_node->bandwidth_up / 10,
> + gw_node->bandwidth_up % 10);
>
> batadv_neigh_node_free_ref(router);
> if (curr_gw)
> batadv_gw_node_free_ref(curr_gw);
> -out:
> - return ret;
> +
> + return seq_overflow(seq);
... and this is utter junk.
This sucker should return 0. Insufficiently large buffer will be handled
by caller, TYVM, if you give that caller a chance to do so. Returning 1
from ->show() is a bug in almost all cases, and definitely so in this one.
Just in case somebody decides that above is worth copying: It Is Not.
Original code is buggy, plain and simple. This one trades the older
bug ("fail with -EINVAL whenever the buffer is too small") with just as buggy
"silently skip an entry entirely whenever the buffer is too small".
Don't Do That.
next prev parent reply other threads:[~2013-12-11 7:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-11 5:12 [PATCH -next 0/3] seq_printf/puts/putc: Start to convert to return void Joe Perches
[not found] ` <cover.1386738050.git.joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org>
2013-12-11 5:12 ` [PATCH -next 2/3] batman-adv: Use seq_overflow Joe Perches
[not found] ` <e7104b35287b1e1ec456734c1b5e1aa98dac99f8.1386738050.git.joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org>
2013-12-11 7:26 ` Antonio Quartulli
[not found] ` <52A813C1.8070404-x4xJYDvStAgysxA8WJXlww@public.gmane.org>
2013-12-11 7:31 ` Antonio Quartulli
[not found] ` <52A814D7.1060805-x4xJYDvStAgysxA8WJXlww@public.gmane.org>
2013-12-11 7:58 ` Al Viro
2013-12-11 7:55 ` Al Viro [this message]
[not found] ` <20131211075526.GR10323-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2013-12-11 8:05 ` Al Viro
[not found] ` <20131211080504.GT10323-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2013-12-11 8:26 ` Joe Perches
2013-12-11 8:38 ` Al Viro
2013-12-11 5:12 ` [PATCH -next 3/3] netfilter: " Joe Perches
2013-12-11 8:17 ` Al Viro
2013-12-11 5:20 ` [PATCH -next 0/3] seq_printf/puts/putc: Start to convert to return void David Miller
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