mac80211: debugfs: calculate free buffer size correctly

In breaking patch buf memory moved from stack to heap and sizeof(buf)
change from size of actual memory to size of the pointer to the heap.

Fix this by holding a separated variable for allocate size.

Fixes: 01f84f0ed3b4 ("mac80211: reduce stack usage in debugfs")
Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Link: https://lore.kernel.org/r/20211021163035.b9ae48c06e27.I6a6ed197110eae28cf4f6e38ce36828a7c136337@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 47 insertions, 44 deletions

diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
index da22725eca0f..481f01b0f65c 100644
--- a/net/mac80211/debugfs_sta.c
+++ b/net/mac80211/debugfs_sta.c
@@ -153,20 +153,20 @@ static ssize_t sta_aqm_read(struct file *file, char __user *userbuf,
 	rcu_read_lock();
 
 	p += scnprintf(p,
-		       bufsz+buf-p,
+		       bufsz + buf - p,
 		       "target %uus interval %uus ecn %s\n",
 		       codel_time_to_us(sta->cparams.target),
 		       codel_time_to_us(sta->cparams.interval),
 		       sta->cparams.ecn ? "yes" : "no");
 	p += scnprintf(p,
-		       bufsz+buf-p,
+		       bufsz + buf - p,
 		       "tid ac backlog-bytes backlog-packets new-flows drops marks overlimit collisions tx-bytes tx-packets flags\n");
 
 	for (i = 0; i < ARRAY_SIZE(sta->sta.txq); i++) {
 		if (!sta->sta.txq[i])
 			continue;
 		txqi = to_txq_info(sta->sta.txq[i]);
-		p += scnprintf(p, bufsz+buf-p,
+		p += scnprintf(p, bufsz + buf - p,
 			       "%d %d %u %u %u %u %u %u %u %u %u 0x%lx(%s%s%s)\n",
 			       txqi->txq.tid,
 			       txqi->txq.ac,
@@ -315,22 +315,23 @@ static ssize_t sta_agg_status_read(struct file *file, char __user *userbuf,
 					size_t count, loff_t *ppos)
 {
 	char *buf, *p;
+	ssize_t bufsz = 71 + IEEE80211_NUM_TIDS * 40;
 	int i;
 	struct sta_info *sta = file->private_data;
 	struct tid_ampdu_rx *tid_rx;
 	struct tid_ampdu_tx *tid_tx;
 	ssize_t ret;
 
-	buf = kzalloc(71 + IEEE80211_NUM_TIDS * 40, GFP_KERNEL);
+	buf = kzalloc(bufsz, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 	p = buf;
 
 	rcu_read_lock();
 
-	p += scnprintf(p, sizeof(buf) + buf - p, "next dialog_token: %#02x\n",
+	p += scnprintf(p, bufsz + buf - p, "next dialog_token: %#02x\n",
 			sta->ampdu_mlme.dialog_token_allocator + 1);
-	p += scnprintf(p, sizeof(buf) + buf - p,
+	p += scnprintf(p, bufsz + buf - p,
 		       "TID\t\tRX\tDTKN\tSSN\t\tTX\tDTKN\tpending\n");
 
 	for (i = 0; i < IEEE80211_NUM_TIDS; i++) {
@@ -340,21 +341,21 @@ static ssize_t sta_agg_status_read(struct file *file, char __user *userbuf,
 		tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[i]);
 		tid_rx_valid = test_bit(i, sta->ampdu_mlme.agg_session_valid);
 
-		p += scnprintf(p, sizeof(buf) + buf - p, "%02d", i);
-		p += scnprintf(p, sizeof(buf) + buf - p, "\t\t%x",
+		p += scnprintf(p, bufsz + buf - p, "%02d", i);
+		p += scnprintf(p, bufsz + buf - p, "\t\t%x",
 			       tid_rx_valid);
-		p += scnprintf(p, sizeof(buf) + buf - p, "\t%#.2x",
+		p += scnprintf(p, bufsz + buf - p, "\t%#.2x",
 			       tid_rx_valid ?
 					sta->ampdu_mlme.tid_rx_token[i] : 0);
-		p += scnprintf(p, sizeof(buf) + buf - p, "\t%#.3x",
+		p += scnprintf(p, bufsz + buf - p, "\t%#.3x",
 				tid_rx ? tid_rx->ssn : 0);
 
-		p += scnprintf(p, sizeof(buf) + buf - p, "\t\t%x", !!tid_tx);
-		p += scnprintf(p, sizeof(buf) + buf - p, "\t%#.2x",
+		p += scnprintf(p, bufsz + buf - p, "\t\t%x", !!tid_tx);
+		p += scnprintf(p, bufsz + buf - p, "\t%#.2x",
 				tid_tx ? tid_tx->dialog_token : 0);
-		p += scnprintf(p, sizeof(buf) + buf - p, "\t%03d",
+		p += scnprintf(p, bufsz + buf - p, "\t%03d",
 				tid_tx ? skb_queue_len(&tid_tx->pending) : 0);
-		p += scnprintf(p, sizeof(buf) + buf - p, "\n");
+		p += scnprintf(p, bufsz + buf - p, "\n");
 	}
 	rcu_read_unlock();
 
@@ -444,19 +445,20 @@ static ssize_t sta_ht_capa_read(struct file *file, char __user *userbuf,
 	} while (0)
 	char *buf, *p;
 	int i;
+	ssize_t bufsz = 512;
 	struct sta_info *sta = file->private_data;
 	struct ieee80211_sta_ht_cap *htc = &sta->sta.ht_cap;
 	ssize_t ret;
 
-	buf = kzalloc(512, GFP_KERNEL);
+	buf = kzalloc(bufsz, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 	p = buf;
 
-	p += scnprintf(p, sizeof(buf) + buf - p, "ht %ssupported\n",
+	p += scnprintf(p, bufsz + buf - p, "ht %ssupported\n",
 			htc->ht_supported ? "" : "not ");
 	if (htc->ht_supported) {
-		p += scnprintf(p, sizeof(buf)+buf-p, "cap: %#.4x\n", htc->cap);
+		p += scnprintf(p, bufsz + buf - p, "cap: %#.4x\n", htc->cap);
 
 		PRINT_HT_CAP((htc->cap & BIT(0)), "RX LDPC");
 		PRINT_HT_CAP((htc->cap & BIT(1)), "HT20/HT40");
@@ -498,23 +500,23 @@ static ssize_t sta_ht_capa_read(struct file *file, char __user *userbuf,
 
 		PRINT_HT_CAP((htc->cap & BIT(15)), "L-SIG TXOP protection");
 
-		p += scnprintf(p, sizeof(buf)+buf-p, "ampdu factor/density: %d/%d\n",
+		p += scnprintf(p, bufsz + buf - p, "ampdu factor/density: %d/%d\n",
 				htc->ampdu_factor, htc->ampdu_density);
-		p += scnprintf(p, sizeof(buf)+buf-p, "MCS mask:");
+		p += scnprintf(p, bufsz + buf - p, "MCS mask:");
 
 		for (i = 0; i < IEEE80211_HT_MCS_MASK_LEN; i++)
-			p += scnprintf(p, sizeof(buf)+buf-p, " %.2x",
+			p += scnprintf(p, bufsz + buf - p, " %.2x",
 					htc->mcs.rx_mask[i]);
-		p += scnprintf(p, sizeof(buf)+buf-p, "\n");
+		p += scnprintf(p, bufsz + buf - p, "\n");
 
 		/* If not set this is meaningless */
 		if (le16_to_cpu(htc->mcs.rx_highest)) {
-			p += scnprintf(p, sizeof(buf)+buf-p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "MCS rx highest: %d Mbps\n",
 				       le16_to_cpu(htc->mcs.rx_highest));
 		}
 
-		p += scnprintf(p, sizeof(buf)+buf-p, "MCS tx params: %x\n",
+		p += scnprintf(p, bufsz + buf - p, "MCS tx params: %x\n",
 				htc->mcs.tx_params);
 	}
 
@@ -531,56 +533,57 @@ static ssize_t sta_vht_capa_read(struct file *file, char __user *userbuf,
 	struct sta_info *sta = file->private_data;
 	struct ieee80211_sta_vht_cap *vhtc = &sta->sta.vht_cap;
 	ssize_t ret;
+	ssize_t bufsz = 512;
 
-	buf = kzalloc(512, GFP_KERNEL);
+	buf = kzalloc(bufsz, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 	p = buf;
 
-	p += scnprintf(p, sizeof(buf) + buf - p, "VHT %ssupported\n",
+	p += scnprintf(p, bufsz + buf - p, "VHT %ssupported\n",
 			vhtc->vht_supported ? "" : "not ");
 	if (vhtc->vht_supported) {
-		p += scnprintf(p, sizeof(buf) + buf - p, "cap: %#.8x\n",
+		p += scnprintf(p, bufsz + buf - p, "cap: %#.8x\n",
 			       vhtc->cap);
 #define PFLAG(a, b)							\
 		do {							\
 			if (vhtc->cap & IEEE80211_VHT_CAP_ ## a)	\
-				p += scnprintf(p, sizeof(buf) + buf - p, \
+				p += scnprintf(p, bufsz + buf - p, \
 					       "\t\t%s\n", b);		\
 		} while (0)
 
 		switch (vhtc->cap & 0x3) {
 		case IEEE80211_VHT_CAP_MAX_MPDU_LENGTH_3895:
-			p += scnprintf(p, sizeof(buf) + buf - p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "\t\tMAX-MPDU-3895\n");
 			break;
 		case IEEE80211_VHT_CAP_MAX_MPDU_LENGTH_7991:
-			p += scnprintf(p, sizeof(buf) + buf - p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "\t\tMAX-MPDU-7991\n");
 			break;
 		case IEEE80211_VHT_CAP_MAX_MPDU_LENGTH_11454:
-			p += scnprintf(p, sizeof(buf) + buf - p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "\t\tMAX-MPDU-11454\n");
 			break;
 		default:
-			p += scnprintf(p, sizeof(buf) + buf - p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "\t\tMAX-MPDU-UNKNOWN\n");
 		}
 		switch (vhtc->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK) {
 		case 0:
-			p += scnprintf(p, sizeof(buf) + buf - p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "\t\t80Mhz\n");
 			break;
 		case IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ:
-			p += scnprintf(p, sizeof(buf) + buf - p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "\t\t160Mhz\n");
 			break;
 		case IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ:
-			p += scnprintf(p, sizeof(buf) + buf - p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "\t\t80+80Mhz\n");
 			break;
 		default:
-			p += scnprintf(p, sizeof(buf) + buf - p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "\t\tUNKNOWN-MHZ: 0x%x\n",
 				       (vhtc->cap >> 2) & 0x3);
 		}
@@ -588,15 +591,15 @@ static ssize_t sta_vht_capa_read(struct file *file, char __user *userbuf,
 		PFLAG(SHORT_GI_80, "SHORT-GI-80");
 		PFLAG(SHORT_GI_160, "SHORT-GI-160");
 		PFLAG(TXSTBC, "TXSTBC");
-		p += scnprintf(p, sizeof(buf) + buf - p,
+		p += scnprintf(p, bufsz + buf - p,
 			       "\t\tRXSTBC_%d\n", (vhtc->cap >> 8) & 0x7);
 		PFLAG(SU_BEAMFORMER_CAPABLE, "SU-BEAMFORMER-CAPABLE");
 		PFLAG(SU_BEAMFORMEE_CAPABLE, "SU-BEAMFORMEE-CAPABLE");
-		p += scnprintf(p, sizeof(buf) + buf - p,
+		p += scnprintf(p, bufsz + buf - p,
 			"\t\tBEAMFORMEE-STS: 0x%x\n",
 			(vhtc->cap & IEEE80211_VHT_CAP_BEAMFORMEE_STS_MASK) >>
 			IEEE80211_VHT_CAP_BEAMFORMEE_STS_SHIFT);
-		p += scnprintf(p, sizeof(buf) + buf - p,
+		p += scnprintf(p, bufsz + buf - p,
 			"\t\tSOUNDING-DIMENSIONS: 0x%x\n",
 			(vhtc->cap & IEEE80211_VHT_CAP_SOUNDING_DIMENSIONS_MASK)
 			>> IEEE80211_VHT_CAP_SOUNDING_DIMENSIONS_SHIFT);
@@ -604,28 +607,28 @@ static ssize_t sta_vht_capa_read(struct file *file, char __user *userbuf,
 		PFLAG(MU_BEAMFORMEE_CAPABLE, "MU-BEAMFORMEE-CAPABLE");
 		PFLAG(VHT_TXOP_PS, "TXOP-PS");
 		PFLAG(HTC_VHT, "HTC-VHT");
-		p += scnprintf(p, sizeof(buf) + buf - p,
+		p += scnprintf(p, bufsz + buf - p,
 			"\t\tMPDU-LENGTH-EXPONENT: 0x%x\n",
 			(vhtc->cap & IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK) >>
 			IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_SHIFT);
 		PFLAG(VHT_LINK_ADAPTATION_VHT_UNSOL_MFB,
 		      "LINK-ADAPTATION-VHT-UNSOL-MFB");
-		p += scnprintf(p, sizeof(buf) + buf - p,
+		p += scnprintf(p, bufsz + buf - p,
 			"\t\tLINK-ADAPTATION-VHT-MRQ-MFB: 0x%x\n",
 			(vhtc->cap & IEEE80211_VHT_CAP_VHT_LINK_ADAPTATION_VHT_MRQ_MFB) >> 26);
 		PFLAG(RX_ANTENNA_PATTERN, "RX-ANTENNA-PATTERN");
 		PFLAG(TX_ANTENNA_PATTERN, "TX-ANTENNA-PATTERN");
 
-		p += scnprintf(p, sizeof(buf)+buf-p, "RX MCS: %.4x\n",
+		p += scnprintf(p, bufsz + buf - p, "RX MCS: %.4x\n",
 			       le16_to_cpu(vhtc->vht_mcs.rx_mcs_map));
 		if (vhtc->vht_mcs.rx_highest)
-			p += scnprintf(p, sizeof(buf)+buf-p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "MCS RX highest: %d Mbps\n",
 				       le16_to_cpu(vhtc->vht_mcs.rx_highest));
-		p += scnprintf(p, sizeof(buf)+buf-p, "TX MCS: %.4x\n",
+		p += scnprintf(p, bufsz + buf - p, "TX MCS: %.4x\n",
 			       le16_to_cpu(vhtc->vht_mcs.tx_mcs_map));
 		if (vhtc->vht_mcs.tx_highest)
-			p += scnprintf(p, sizeof(buf)+buf-p,
+			p += scnprintf(p, bufsz + buf - p,
 				       "MCS TX highest: %d Mbps\n",
 				       le16_to_cpu(vhtc->vht_mcs.tx_highest));
 #undef PFLAG