Commit 4aeb6967 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
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tracing: Replace typecasted void pointer in set_ftrace_filter code 



The set_ftrace_filter uses seq_file and reads from two lists. The
pointer returned by t_next() can either be of type struct dyn_ftrace
or struct ftrace_func_probe. If there is a bug (there was one)
the wrong pointer may be used and the reference can cause an oops.

This patch makes t_next() and friends only return the iterator structure
which now has a pointer of type struct dyn_ftrace and struct
ftrace_func_probe. The t_show() can now test if the pointer is NULL or
not and if the pointer exists, it is guaranteed to be of the correct type.

Now if there's a bug, only wrong data will be shown but not an oops.

Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 2bccfffd

kernel/trace/ftrace.c

+46 −21
Original line number Diff line number Diff line
@@ -1370,23 +1370,27 @@ enum { 
struct ftrace_iterator {

	loff_t				func_pos;

	struct ftrace_page		*pg;

	struct dyn_ftrace		*func;

	struct ftrace_func_probe	*probe;

	struct trace_parser		parser;

	int				hidx;

	int				idx;

	unsigned			flags;

	struct trace_parser	parser;

};



static void *

t_hash_next(struct seq_file *m, void *v, loff_t *pos)

t_hash_next(struct seq_file *m, loff_t *pos)

{

	struct ftrace_iterator *iter = m->private;

	struct hlist_node *hnd = v;

	struct hlist_node *hnd = NULL;

	struct hlist_head *hhd;



	WARN_ON(!(iter->flags & FTRACE_ITER_HASH));



	(*pos)++;



	if (iter->probe)

		hnd = &iter->probe->node;

 retry:

	if (iter->hidx >= FTRACE_FUNC_HASHSIZE)

		return NULL;
@@ -1409,7 +1413,12 @@ t_hash_next(struct seq_file *m, void *v, loff_t *pos) 
		}

	}



	return hnd;

	if (WARN_ON_ONCE(!hnd))

		return NULL;



	iter->probe = hlist_entry(hnd, struct ftrace_func_probe, node);



	return iter;

}



static void *t_hash_start(struct seq_file *m, loff_t *pos)
@@ -1428,19 +1437,24 @@ static void *t_hash_start(struct seq_file *m, loff_t *pos) 


	iter->hidx = 0;

	for (l = 0; l <= (*pos - iter->func_pos); ) {

		p = t_hash_next(m, p, &l);

		p = t_hash_next(m, &l);

		if (!p)

			break;

	}

	return p;

	if (!p)

		return NULL;



	return iter;

}



static int t_hash_show(struct seq_file *m, void *v)

static int

t_hash_show(struct seq_file *m, struct ftrace_iterator *iter)

{

	struct ftrace_func_probe *rec;

	struct hlist_node *hnd = v;



	rec = hlist_entry(hnd, struct ftrace_func_probe, node);

	rec = iter->probe;

	if (WARN_ON_ONCE(!rec))

		return -EIO;



	if (rec->ops->print)

		return rec->ops->print(m, rec->ip, rec->ops, rec->data);
@@ -1461,7 +1475,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos) 
	struct dyn_ftrace *rec = NULL;



	if (iter->flags & FTRACE_ITER_HASH)

		return t_hash_next(m, v, pos);

		return t_hash_next(m, pos);



	(*pos)++;
@@ -1495,7 +1509,12 @@ t_next(struct seq_file *m, void *v, loff_t *pos) 
		}

	}



	return rec;

	if (!rec)

		return NULL;



	iter->func = rec;



	return iter;

}



static void *t_start(struct seq_file *m, loff_t *pos)
@@ -1530,10 +1549,14 @@ static void *t_start(struct seq_file *m, loff_t *pos) 
			break;

	}



	if (!p && iter->flags & FTRACE_ITER_FILTER)

	if (!p) {

		if (iter->flags & FTRACE_ITER_FILTER)

			return t_hash_start(m, pos);



	return p;

		return NULL;

	}



	return iter;

}



static void t_stop(struct seq_file *m, void *p)
@@ -1544,16 +1567,18 @@ static void t_stop(struct seq_file *m, void *p) 
static int t_show(struct seq_file *m, void *v)

{

	struct ftrace_iterator *iter = m->private;

	struct dyn_ftrace *rec = v;

	struct dyn_ftrace *rec;



	if (iter->flags & FTRACE_ITER_HASH)

		return t_hash_show(m, v);

		return t_hash_show(m, iter);



	if (iter->flags & FTRACE_ITER_PRINTALL) {

		seq_printf(m, "#### all functions enabled ####\n");

		return 0;

	}



	rec = iter->func;



	if (!rec)

		return 0;

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