net/wireless/nl80211.c: Avoid call to genlmsg_cancel (efe1cf0c) · Commits · 戴 / test

genlmsg_cancel subtracts some constants from its second argument before calling nlmsg_cancel. nlmsg_cancel then calls nlmsg_trim on the same arguments. nlmsg_trim tests for NULL before doing any computation, but a NULL second argument to genlmsg_cancel is no longer NULL due to the initial subtraction. Nothing else happens in this execution, so the call to genlmsg_cancel is simply unnecessary in this case. The semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/ ) // <smpl> @@ expression data; @@ if (data == NULL) { ... * genlmsg_cancel(..., data); ... return ...; } // </smpl> Signed-off-by:

Julia Lawall <julia@diku.dk> Signed-off-by:

John W. Linville <linville@tuxdriver.com>

net/wireless/nl80211.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -2718,7 +2718,7 @@ static int nl80211_get_mesh_config(struct sk_buff *skb,
		hdr = nl80211hdr_put(msg, info->snd_pid, info->snd_seq, 0,
		NL80211_CMD_GET_MESH_CONFIG);
		if (!hdr)
		goto nla_put_failure;
		goto out;
		pinfoattr = nla_nest_start(msg, NL80211_ATTR_MESH_CONFIG);
		if (!pinfoattr)
		goto nla_put_failure;
		@@ -2759,6 +2759,7 @@ static int nl80211_get_mesh_config(struct sk_buff *skb,

		nla_put_failure:
		genlmsg_cancel(msg, hdr);
		out:
		nlmsg_free(msg);
		return -ENOBUFS;
		}
		@@ -2954,7 +2955,7 @@ static int nl80211_get_reg(struct sk_buff skb, struct genl_info info)
		hdr = nl80211hdr_put(msg, info->snd_pid, info->snd_seq, 0,
		NL80211_CMD_GET_REG);
		if (!hdr)
		goto nla_put_failure;
		goto put_failure;

		NLA_PUT_STRING(msg, NL80211_ATTR_REG_ALPHA2,
		cfg80211_regdomain->alpha2);
		@@ -3001,6 +3002,7 @@ static int nl80211_get_reg(struct sk_buff skb, struct genl_info info)

		nla_put_failure:
		genlmsg_cancel(msg, hdr);
		put_failure:
		nlmsg_free(msg);
		err = -EMSGSIZE;
		out:

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