1 files changed, 45 insertions, 20 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ce11fa5..1af4f8f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -939,19 +939,20 @@ out:
 	return ret;
 }
 
+/* TODO add a seq_buf_to_buffer() */
 static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 {
 	int len;
 
-	if (s->len <= s->readpos)
+	if (trace_seq_used(s) <= s->seq.readpos)
 		return -EBUSY;
 
-	len = s->len - s->readpos;
+	len = trace_seq_used(s) - s->seq.readpos;
 	if (cnt > len)
 		cnt = len;
-	memcpy(buf, s->buffer + s->readpos, cnt);
+	memcpy(buf, s->buffer + s->seq.readpos, cnt);
 
-	s->readpos += cnt;
+	s->seq.readpos += cnt;
 	return cnt;
 }
 
@@ -4313,6 +4314,8 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
 		goto out;
 	}
 
+	trace_seq_init(&iter->seq);
+
 	/*
 	 * We make a copy of the current tracer to avoid concurrent
 	 * changes on it while we are reading.
@@ -4506,18 +4509,18 @@ waitagain:
 	trace_access_lock(iter->cpu_file);
 	while (trace_find_next_entry_inc(iter) != NULL) {
 		enum print_line_t ret;
-		int len = iter->seq.len;
+		int save_len = iter->seq.seq.len;
 
 		ret = print_trace_line(iter);
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
 			/* don't print partial lines */
-			iter->seq.len = len;
+			iter->seq.seq.len = save_len;
 			break;
 		}
 		if (ret != TRACE_TYPE_NO_CONSUME)
 			trace_consume(iter);
 
-		if (iter->seq.len >= cnt)
+		if (trace_seq_used(&iter->seq) >= cnt)
 			break;
 
 		/*
@@ -4533,7 +4536,7 @@ waitagain:
 
 	/* Now copy what we have to the user */
 	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
-	if (iter->seq.readpos >= iter->seq.len)
+	if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
 		trace_seq_init(&iter->seq);
 
 	/*
@@ -4567,20 +4570,33 @@ static size_t
 tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 {
 	size_t count;
+	int save_len;
 	int ret;
 
 	/* Seq buffer is page-sized, exactly what we need. */
 	for (;;) {
-		count = iter->seq.len;
+		save_len = iter->seq.seq.len;
 		ret = print_trace_line(iter);
-		count = iter->seq.len - count;
-		if (rem < count) {
-			rem = 0;
-			iter->seq.len -= count;
+
+		if (trace_seq_has_overflowed(&iter->seq)) {
+			iter->seq.seq.len = save_len;
 			break;
 		}
+
+		/*
+		 * This should not be hit, because it should only
+		 * be set if the iter->seq overflowed. But check it
+		 * anyway to be safe.
+		 */
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
-			iter->seq.len -= count;
+			iter->seq.seq.len = save_len;
+			break;
+		}
+
+		count = trace_seq_used(&iter->seq) - save_len;
+		if (rem < count) {
+			rem = 0;
+			iter->seq.seq.len = save_len;
 			break;
 		}
 
@@ -4661,13 +4677,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		/* Copy the data into the page, so we can start over. */
 		ret = trace_seq_to_buffer(&iter->seq,
 					  page_address(spd.pages[i]),
-					  iter->seq.len);
+					  trace_seq_used(&iter->seq));
 		if (ret < 0) {
 			__free_page(spd.pages[i]);
 			break;
 		}
 		spd.partial[i].offset = 0;
-		spd.partial[i].len = iter->seq.len;
+		spd.partial[i].len = trace_seq_used(&iter->seq);
 
 		trace_seq_init(&iter->seq);
 	}
@@ -5667,7 +5683,8 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 	cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "read events: %ld\n", cnt);
 
-	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
+	count = simple_read_from_buffer(ubuf, count, ppos,
+					s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
@@ -6630,11 +6647,19 @@ void
 trace_printk_seq(struct trace_seq *s)
 {
 	/* Probably should print a warning here. */
-	if (s->len >= TRACE_MAX_PRINT)
-		s->len = TRACE_MAX_PRINT;
+	if (s->seq.len >= TRACE_MAX_PRINT)
+		s->seq.len = TRACE_MAX_PRINT;
+
+	/*
+	 * More paranoid code. Although the buffer size is set to
+	 * PAGE_SIZE, and TRACE_MAX_PRINT is 1000, this is just
+	 * an extra layer of protection.
+	 */
+	if (WARN_ON_ONCE(s->seq.len >= s->seq.size))
+		s->seq.len = s->seq.size - 1;
 
 	/* should be zero ended, but we are paranoid. */
-	s->buffer[s->len] = 0;
+	s->buffer[s->seq.len] = 0;
 
 	printk(KERN_TRACE "%s", s->buffer);