ath5k: snprintf() returns largish values

snprintf() returns the number of characters that would have been written
(not counting the NUL character).  So we can't use it as the limiter to
simple_read_from_buffer() without capping it first at sizeof(buf).
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/debug.c

@@ -239,6 +239,9 @@ static ssize_t read_file_beacon(struct file *file, char __user *user_buf,
 		"TSF\t\t0x%016llx\tTU: %08x\n",
 		(unsigned long long)tsf, TSF_TO_TU(tsf));
 
+	if (len > sizeof(buf))
+		len = sizeof(buf);
+
 	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 }
 
@@ -334,6 +337,9 @@ static ssize_t read_file_debug(struct file *file, char __user *user_buf,
 		sc->debug.level == dbg_info[i].level ? '+' : ' ',
 		dbg_info[i].level, dbg_info[i].desc);
 
+	if (len > sizeof(buf))
+		len = sizeof(buf);
+
 	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 }
 
@@ -433,6 +439,9 @@ static ssize_t read_file_antenna(struct file *file, char __user *user_buf,
 	len += snprintf(buf+len, sizeof(buf)-len,
 			"AR5K_PHY_ANT_SWITCH_TABLE_1\t0x%08x\n", v);
 
+	if (len > sizeof(buf))
+		len = sizeof(buf);
+
 	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 }
 
@@ -542,6 +551,9 @@ static ssize_t read_file_frameerrors(struct file *file, char __user *user_buf,
 	len += snprintf(buf+len, sizeof(buf)-len, "[TX all\t%d]\n",
 			st->tx_all_count);
 
+	if (len > sizeof(buf))
+		len = sizeof(buf);
+
 	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 }
 
@@ -681,6 +693,9 @@ static ssize_t read_file_ani(struct file *file, char __user *user_buf,
 			ATH5K_ANI_CCK_TRIG_HIGH - (ATH5K_PHYERR_CNT_MAX -
 			ath5k_hw_reg_read(sc->ah, AR5K_PHYERR_CNT2)));
 
+	if (len > sizeof(buf))
+		len = sizeof(buf);
+
 	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 }
 
@@ -766,6 +781,9 @@ static ssize_t read_file_queue(struct file *file, char __user *user_buf,
 		len += snprintf(buf+len, sizeof(buf)-len, "  len: %d\n", n);
 	}
 
+	if (len > sizeof(buf))
+		len = sizeof(buf);
+
 	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 }