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Date:   Thu, 23 Sep 2021 16:25:36 +0800
From:   Wen Gong <wgong@codeaurora.org>
To:     johannes@sipsolutions.net, ath11k@lists.infradead.org
Cc:     linux-wireless@vger.kernel.org
Subject: Re: [PATCH v3 8/9] mac80211: use ieee802_11_parse_elems() to find ies
 instead of ieee80211_bss_get_ie()
In-Reply-To: <20210903114821.23346-9-wgong@codeaurora.org>
References: <20210903114821.23346-1-wgong@codeaurora.org>
 <20210903114821.23346-9-wgong@codeaurora.org>
Message-ID: <3ed7ae36af1e753e1b072a845b8f2dc2@codeaurora.org>
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Hi Johannes,

This patch need a new version for fix the issue of NULL pointer it 
exist.
You can review others:)

The change I will add in new version is like below.

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 0ebf6ae6dd525f..bee2a3f3bbc161 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -5026,11 +5026,15 @@ static int ieee80211_prep_channel(struct 
ieee80211_sub_if_data *sdata,
         if (!(ifmgd->flags & IEEE80211_STA_DISABLE_HT) && !is_6ghz) {
                 const u8 *ht_oper_ie, *ht_cap_ie;

-               ht_oper_ie = ((const u8 *)elems->ht_operation) - 2;
+               ht_oper_ie = elems->ht_operation ?
+                       ((const u8 *)elems->ht_operation) - 2 :
+                       NULL;
                 if (ht_oper_ie && ht_oper_ie[1] >= sizeof(*ht_oper))
                         ht_oper = (void *)(ht_oper_ie + 2);

-               ht_cap_ie = ((const u8 *)elems->ht_cap_elem) - 2;
+               ht_cap_ie = elems->ht_cap_elem ?
+                       ((const u8 *)elems->ht_cap_elem) - 2 :
+                       NULL;
                 if (ht_cap_ie && ht_cap_ie[1] >= sizeof(*ht_cap))
                         ht_cap = (void *)(ht_cap_ie + 2);

@@ -5043,7 +5047,9 @@ static int ieee80211_prep_channel(struct 
ieee80211_sub_if_data *sdata,
         if (!(ifmgd->flags & IEEE80211_STA_DISABLE_VHT) && !is_6ghz) {
                 const u8 *vht_oper_ie, *vht_cap;

-               vht_oper_ie = ((const u8 *)elems->vht_operation) - 2;
+               vht_oper_ie = elems->vht_operation ?
+                       ((const u8 *)elems->vht_operation) - 2 :
+                       NULL;
                 if (vht_oper_ie && vht_oper_ie[1] >= sizeof(*vht_oper))
                         vht_oper = (void *)(vht_oper_ie + 2);
                 if (vht_oper && !ht_oper) {
@@ -5055,7 +5061,9 @@ static int ieee80211_prep_channel(struct 
ieee80211_sub_if_data *sdata,
                         ifmgd->flags |= IEEE80211_STA_DISABLE_HE;
                 }

-               vht_cap = ((const u8 *)elems->vht_cap_elem) - 2;
+               vht_cap = elems->vht_cap_elem ?
+                       ((const u8 *)elems->vht_cap_elem) - 2 :
+                       NULL;
                 if (!vht_cap || vht_cap[1] < sizeof(struct 
ieee80211_vht_cap)) {
                         ifmgd->flags |= IEEE80211_STA_DISABLE_VHT;
                         vht_oper = NULL;
@@ -5065,7 +5073,9 @@ static int ieee80211_prep_channel(struct 
ieee80211_sub_if_data *sdata,
         if (!(ifmgd->flags & IEEE80211_STA_DISABLE_HE)) {
                 const u8 *he_oper_ie;

-               he_oper_ie = ((const u8 *)elems->he_operation) - 3;
+               he_oper_ie = elems->he_operation ?
+                       ((const u8 *)elems->he_operation) - 3 :
+                       NULL;
                 if (he_oper_ie &&
                     he_oper_ie[1] >= 
ieee80211_he_oper_size(&he_oper_ie[3]))
                         he_oper = (void *)(he_oper_ie + 3);
@@ -5117,7 +5127,9 @@ static int ieee80211_prep_channel(struct 
ieee80211_sub_if_data *sdata,
         if (sband->band == NL80211_BAND_S1GHZ) {
                 const u8 *s1g_oper_ie;

-               s1g_oper_ie = ((const u8 *)elems->s1g_oper) - 2;
+               s1g_oper_ie = elems->s1g_oper ?
+                       ((const u8 *)elems->s1g_oper) - 2 :
+                       NULL;
                 if (s1g_oper_ie && s1g_oper_ie[1] >= sizeof(*s1g_oper))
                         s1g_oper = (void *)(s1g_oper_ie + 2);
                 else


On 2021-09-03 19:48, Wen Gong wrote:
> In function ieee80211_prep_channel(), it has some 
> ieee80211_bss_get_ie()
> and cfg80211_find_ext_ie() to get the IE, this is to use another
> function ieee802_11_parse_elems() to get all the IEs in one time.
> 
> Signed-off-by: Wen Gong <wgong@codeaurora.org>
> ---
>  net/mac80211/mlme.c | 40 ++++++++++++++++++++++++----------------
>  1 file changed, 24 insertions(+), 16 deletions(-)
> 
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index 2480bd0577bb..6b32cdd590cd 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -5001,10 +5001,22 @@ static int ieee80211_prep_channel(struct
> ieee80211_sub_if_data *sdata,
>  	bool is_6ghz = cbss->channel->band == NL80211_BAND_6GHZ;
>  	bool is_5ghz = cbss->channel->band == NL80211_BAND_5GHZ;
>  	struct ieee80211_bss *bss = (void *)cbss->priv;
> +	struct ieee802_11_elems *elems;
> +	const struct cfg80211_bss_ies *ies;
>  	int ret;
>  	u32 i;
>  	bool have_80mhz;
> 
> +	elems = kzalloc(sizeof(*elems), GFP_KERNEL);
> +	if (!elems)
> +		return -ENOMEM;
> +
> +	rcu_read_lock();
> +
> +	ies = rcu_dereference(cbss->ies);
> +	ieee802_11_parse_elems(ies->data, ies->len, false, elems,
> +			       NULL, NULL);
> +
>  	sband = local->hw.wiphy->bands[cbss->channel->band];
> 
>  	ifmgd->flags &= ~(IEEE80211_STA_DISABLE_40MHZ |
> @@ -5026,16 +5038,14 @@ static int ieee80211_prep_channel(struct
> ieee80211_sub_if_data *sdata,
>  	if (!ieee80211_get_he_sta_cap(sband))
>  		ifmgd->flags |= IEEE80211_STA_DISABLE_HE;
> 
> -	rcu_read_lock();
> -
>  	if (!(ifmgd->flags & IEEE80211_STA_DISABLE_HT) && !is_6ghz) {
>  		const u8 *ht_oper_ie, *ht_cap_ie;
> 
> -		ht_oper_ie = ieee80211_bss_get_ie(cbss, WLAN_EID_HT_OPERATION);
> +		ht_oper_ie = ((const u8 *)elems->ht_operation) - 2;
>  		if (ht_oper_ie && ht_oper_ie[1] >= sizeof(*ht_oper))
>  			ht_oper = (void *)(ht_oper_ie + 2);
> 
> -		ht_cap_ie = ieee80211_bss_get_ie(cbss, WLAN_EID_HT_CAPABILITY);
> +		ht_cap_ie = ((const u8 *)elems->ht_cap_elem) - 2;
>  		if (ht_cap_ie && ht_cap_ie[1] >= sizeof(*ht_cap))
>  			ht_cap = (void *)(ht_cap_ie + 2);
> 
> @@ -5048,8 +5058,7 @@ static int ieee80211_prep_channel(struct
> ieee80211_sub_if_data *sdata,
>  	if (!(ifmgd->flags & IEEE80211_STA_DISABLE_VHT) && !is_6ghz) {
>  		const u8 *vht_oper_ie, *vht_cap;
> 
> -		vht_oper_ie = ieee80211_bss_get_ie(cbss,
> -						   WLAN_EID_VHT_OPERATION);
> +		vht_oper_ie = ((const u8 *)elems->vht_operation) - 2;
>  		if (vht_oper_ie && vht_oper_ie[1] >= sizeof(*vht_oper))
>  			vht_oper = (void *)(vht_oper_ie + 2);
>  		if (vht_oper && !ht_oper) {
> @@ -5061,7 +5070,7 @@ static int ieee80211_prep_channel(struct
> ieee80211_sub_if_data *sdata,
>  			ifmgd->flags |= IEEE80211_STA_DISABLE_HE;
>  		}
> 
> -		vht_cap = ieee80211_bss_get_ie(cbss, WLAN_EID_VHT_CAPABILITY);
> +		vht_cap = ((const u8 *)elems->vht_cap_elem) - 2;
>  		if (!vht_cap || vht_cap[1] < sizeof(struct ieee80211_vht_cap)) {
>  			ifmgd->flags |= IEEE80211_STA_DISABLE_VHT;
>  			vht_oper = NULL;
> @@ -5069,12 +5078,9 @@ static int ieee80211_prep_channel(struct
> ieee80211_sub_if_data *sdata,
>  	}
> 
>  	if (!(ifmgd->flags & IEEE80211_STA_DISABLE_HE)) {
> -		const struct cfg80211_bss_ies *ies;
>  		const u8 *he_oper_ie;
> 
> -		ies = rcu_dereference(cbss->ies);
> -		he_oper_ie = cfg80211_find_ext_ie(WLAN_EID_EXT_HE_OPERATION,
> -						  ies->data, ies->len);
> +		he_oper_ie = ((const u8 *)elems->he_operation) - 3;
>  		if (he_oper_ie &&
>  		    he_oper_ie[1] >= ieee80211_he_oper_size(&he_oper_ie[3]))
>  			he_oper = (void *)(he_oper_ie + 3);
> @@ -5102,8 +5108,7 @@ static int ieee80211_prep_channel(struct
> ieee80211_sub_if_data *sdata,
>  	if (sband->band == NL80211_BAND_S1GHZ) {
>  		const u8 *s1g_oper_ie;
> 
> -		s1g_oper_ie = ieee80211_bss_get_ie(cbss,
> -						   WLAN_EID_S1G_OPERATION);
> +		s1g_oper_ie = ((const u8 *)elems->s1g_oper) - 2;
>  		if (s1g_oper_ie && s1g_oper_ie[1] >= sizeof(*s1g_oper))
>  			s1g_oper = (void *)(s1g_oper_ie + 2);
>  		else
> @@ -5125,7 +5130,8 @@ static int ieee80211_prep_channel(struct
> ieee80211_sub_if_data *sdata,
> 
>  	if (ifmgd->flags & IEEE80211_STA_DISABLE_HE && is_6ghz) {
>  		sdata_info(sdata, "Rejecting non-HE 6/7 GHz connection");
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto out_no_lock;
>  	}
> 
>  	/* will change later if needed */
> @@ -5143,15 +5149,17 @@ static int ieee80211_prep_channel(struct
> ieee80211_sub_if_data *sdata,
>  	/* don't downgrade for 5 and 10 MHz channels, though. */
>  	if (chandef.width == NL80211_CHAN_WIDTH_5 ||
>  	    chandef.width == NL80211_CHAN_WIDTH_10)
> -		goto out;
> +		goto out_lock;
> 
>  	while (ret && chandef.width != NL80211_CHAN_WIDTH_20_NOHT) {
>  		ifmgd->flags |= ieee80211_chandef_downgrade(&chandef);
>  		ret = ieee80211_vif_use_channel(sdata, &chandef,
>  						IEEE80211_CHANCTX_SHARED);
>  	}
> - out:
> + out_lock:
>  	mutex_unlock(&local->mtx);
> + out_no_lock:
> +	kfree(elems);
>  	return ret;
>  }