Commit 5ac48378 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt

tracing: Use trace_seq_used() and seq_buf_used() instead of len

As the seq_buf->len will soon be +1 size when there's an overflow, we
must use trace_seq_used() or seq_buf_used() methods to get the real
length. This will prevent buffer overflow issues if just the len
of the seq_buf descriptor is used to copy memory.

Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.homeReported-by: default avatarPetr Mladek <pmladek@suse.cz>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 74f06bb7
......@@ -23,6 +23,24 @@ trace_seq_init(struct trace_seq *s)
s->full = 0;
}
/**
* trace_seq_used - amount of actual data written to buffer
* @s: trace sequence descriptor
*
* Returns the amount of data written to the buffer.
*
* IMPORTANT!
*
* Use this instead of @s->seq.len if you need to pass the amount
* of data from the buffer to another buffer (userspace, or what not).
* The @s->seq.len on overflow is bigger than the buffer size and
* using it can cause access to undefined memory.
*/
static inline int trace_seq_used(struct trace_seq *s)
{
return seq_buf_used(&s->seq);
}
/**
* trace_seq_buffer_ptr - return pointer to next location in buffer
* @s: trace sequence descriptor
......@@ -35,7 +53,7 @@ trace_seq_init(struct trace_seq *s)
static inline unsigned char *
trace_seq_buffer_ptr(struct trace_seq *s)
{
return s->buffer + s->seq.len;
return s->buffer + seq_buf_used(&s->seq);
}
/**
......
......@@ -328,7 +328,7 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
if (s->len <= s->readpos)
return -EBUSY;
len = s->len - s->readpos;
len = seq_buf_used(s) - s->readpos;
if (cnt > len)
cnt = len;
ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
......
......@@ -944,10 +944,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
int len;
if (s->seq.len <= s->seq.readpos)
if (trace_seq_used(s) <= s->seq.readpos)
return -EBUSY;
len = s->seq.len - s->seq.readpos;
len = trace_seq_used(s) - s->seq.readpos;
if (cnt > len)
cnt = len;
memcpy(buf, s->buffer + s->seq.readpos, cnt);
......@@ -4514,18 +4514,18 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
trace_access_lock(iter->cpu_file);
while (trace_find_next_entry_inc(iter) != NULL) {
enum print_line_t ret;
int len = iter->seq.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.seq.len = len;
iter->seq.seq.len = save_len;
break;
}
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
if (iter->seq.seq.len >= cnt)
if (trace_seq_used(&iter->seq) >= cnt)
break;
/*
......@@ -4541,7 +4541,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
/* Now copy what we have to the user */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (iter->seq.seq.readpos >= iter->seq.seq.len)
if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
trace_seq_init(&iter->seq);
/*
......@@ -4598,7 +4598,7 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
break;
}
count = iter->seq.seq.len - save_len;
count = trace_seq_used(&iter->seq) - save_len;
if (rem < count) {
rem = 0;
iter->seq.seq.len = save_len;
......@@ -4682,13 +4682,13 @@ 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.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.seq.len;
spd.partial[i].len = trace_seq_used(&iter->seq);
trace_seq_init(&iter->seq);
}
......@@ -5689,7 +5689,8 @@ 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->seq.len);
count = simple_read_from_buffer(ubuf, count, ppos,
s->buffer, trace_seq_used(s));
kfree(s);
......
......@@ -1044,7 +1044,8 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
mutex_unlock(&event_mutex);
if (file)
r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
r = simple_read_from_buffer(ubuf, cnt, ppos,
s->buffer, trace_seq_used(s));
kfree(s);
......@@ -1210,7 +1211,8 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
trace_seq_init(s);
print_subsystem_event_filter(system, s);
r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
r = simple_read_from_buffer(ubuf, cnt, ppos,
s->buffer, trace_seq_used(s));
kfree(s);
......@@ -1265,7 +1267,8 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
trace_seq_init(s);
func(s);
r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
r = simple_read_from_buffer(ubuf, cnt, ppos,
s->buffer, trace_seq_used(s));
kfree(s);
......
......@@ -1153,6 +1153,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
return ret;
}
if (trace_seq_has_overflowed(s))
goto out;
/* Strip ending newline */
if (s->buffer[s->seq.len - 1] == '\n') {
s->buffer[s->seq.len - 1] = '\0';
......@@ -1160,7 +1163,7 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
}
trace_seq_puts(s, " */\n");
out:
return trace_handle_return(s);
}
......
......@@ -30,7 +30,7 @@
#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
/* How much buffer is written? */
#define TRACE_SEQ_BUF_USED(s) min((s)->seq.len, (unsigned int)(PAGE_SIZE - 1))
#define TRACE_SEQ_BUF_USED(s) seq_buf_used(&(s)->seq)
/*
* trace_seq should work with being initialized with 0s.
......
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