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From:   Kees Cook <keescook@chromium.org>
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Subject: [PATCH 13/32] mac80211: Use mem_to_flex_dup() with several structs
Date:   Tue,  3 May 2022 18:44:22 -0700
Message-Id: <20220504014440.3697851-14-keescook@chromium.org>
In-Reply-To: <20220504014440.3697851-1-keescook@chromium.org>
References: <20220504014440.3697851-1-keescook@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

As part of the work to perform bounds checking on all memcpy() uses,
replace the open-coded a deserialization of bytes out of memory into a
trailing flexible array by using a flex_array.h helper to perform the
allocation, bounds checking, and copying:

    struct probe_resp
    struct fils_discovery_data
    struct unsol_bcast_probe_resp_data

Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 net/mac80211/cfg.c         | 22 ++++++----------------
 net/mac80211/ieee80211_i.h | 12 ++++++------
 2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index f1d211e61e49..355edbf41707 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -867,20 +867,16 @@ ieee80211_set_probe_resp(struct ieee80211_sub_if_data *sdata,
 			 const struct ieee80211_csa_settings *csa,
 			 const struct ieee80211_color_change_settings *cca)
 {
-	struct probe_resp *new, *old;
+	struct probe_resp *new = NULL, *old;
 
 	if (!resp || !resp_len)
 		return 1;
 
 	old = sdata_dereference(sdata->u.ap.probe_resp, sdata);
 
-	new = kzalloc(sizeof(struct probe_resp) + resp_len, GFP_KERNEL);
-	if (!new)
+	if (mem_to_flex_dup(&new, resp, resp_len, GFP_KERNEL))
 		return -ENOMEM;
 
-	new->len = resp_len;
-	memcpy(new->data, resp, resp_len);
-
 	if (csa)
 		memcpy(new->cntdwn_counter_offsets, csa->counter_offsets_presp,
 		       csa->n_counter_offsets_presp *
@@ -898,7 +894,7 @@ ieee80211_set_probe_resp(struct ieee80211_sub_if_data *sdata,
 static int ieee80211_set_fils_discovery(struct ieee80211_sub_if_data *sdata,
 					struct cfg80211_fils_discovery *params)
 {
-	struct fils_discovery_data *new, *old = NULL;
+	struct fils_discovery_data *new = NULL, *old = NULL;
 	struct ieee80211_fils_discovery *fd;
 
 	if (!params->tmpl || !params->tmpl_len)
@@ -909,11 +905,8 @@ static int ieee80211_set_fils_discovery(struct ieee80211_sub_if_data *sdata,
 	fd->max_interval = params->max_interval;
 
 	old = sdata_dereference(sdata->u.ap.fils_discovery, sdata);
-	new = kzalloc(sizeof(*new) + params->tmpl_len, GFP_KERNEL);
-	if (!new)
+	if (mem_to_flex_dup(&new, params->tmpl, params->tmpl_len, GFP_KERNEL))
 		return -ENOMEM;
-	new->len = params->tmpl_len;
-	memcpy(new->data, params->tmpl, params->tmpl_len);
 	rcu_assign_pointer(sdata->u.ap.fils_discovery, new);
 
 	if (old)
@@ -926,17 +919,14 @@ static int
 ieee80211_set_unsol_bcast_probe_resp(struct ieee80211_sub_if_data *sdata,
 				     struct cfg80211_unsol_bcast_probe_resp *params)
 {
-	struct unsol_bcast_probe_resp_data *new, *old = NULL;
+	struct unsol_bcast_probe_resp_data *new = NULL, *old = NULL;
 
 	if (!params->tmpl || !params->tmpl_len)
 		return -EINVAL;
 
 	old = sdata_dereference(sdata->u.ap.unsol_bcast_probe_resp, sdata);
-	new = kzalloc(sizeof(*new) + params->tmpl_len, GFP_KERNEL);
-	if (!new)
+	if (mem_to_flex_dup(&new, params->tmpl, params->tmpl_len, GFP_KERNEL))
 		return -ENOMEM;
-	new->len = params->tmpl_len;
-	memcpy(new->data, params->tmpl, params->tmpl_len);
 	rcu_assign_pointer(sdata->u.ap.unsol_bcast_probe_resp, new);
 
 	if (old)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index d4a7ba4a8202..2e9bbfb12c0d 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -263,21 +263,21 @@ struct beacon_data {
 
 struct probe_resp {
 	struct rcu_head rcu_head;
-	int len;
+	DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(int, len);
 	u16 cntdwn_counter_offsets[IEEE80211_MAX_CNTDWN_COUNTERS_NUM];
-	u8 data[];
+	DECLARE_FLEX_ARRAY_ELEMENTS(u8, data);
 };
 
 struct fils_discovery_data {
 	struct rcu_head rcu_head;
-	int len;
-	u8 data[];
+	DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(int, len);
+	DECLARE_FLEX_ARRAY_ELEMENTS(u8, data);
 };
 
 struct unsol_bcast_probe_resp_data {
 	struct rcu_head rcu_head;
-	int len;
-	u8 data[];
+	DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(int, len);
+	DECLARE_FLEX_ARRAY_ELEMENTS(u8, data);
 };
 
 struct ps_data {
-- 
2.32.0