Commit ed5467da authored Aug 02, 2013 by Andrew Vagin Committed by Steven Rostedt Aug 02, 2013

tracing: Fix fields of struct trace_iterator that are zeroed by mistake

tracing_read_pipe zeros all fields bellow "seq". The declaration contains
a comment about that, but it doesn't help.

The first field is "snapshot", it's true when current open file is
snapshot. Looks obvious, that it should not be zeroed.

The second field is "started". It was converted from cpumask_t to
cpumask_var_t (v2.6.28-4983-g4462344), in other words it was
converted from cpumask to pointer on cpumask.

Currently the reference on "started" memory is lost after the first read
from tracing_read_pipe and a proper object will never be freed.

The "started" is never dereferenced for trace_pipe, because trace_pipe
can't have the TRACE_FILE_ANNOTATE options.

Link: http://lkml.kernel.org/r/1375463803-3085183-1-git-send-email-avagin@openvz.org



Cc: stable@vger.kernel.org # 2.6.30
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent c6c2401d

include/linux/ftrace_event.h

+6 −4

Original line number	Diff line number	Diff line
		@@ -78,6 +78,11 @@ struct trace_iterator {
		/* trace_seq for __print_flags() and __print_symbolic() etc. */
		struct trace_seq tmp_seq;

		cpumask_var_t started;

		/* it's true when current open file is snapshot */
		bool snapshot;

		/* The below is zeroed out in pipe_read */
		struct trace_seq seq;
		struct trace_entry *ent;
		@@ -90,10 +95,7 @@ struct trace_iterator {
		loff_t pos;
		long idx;

		cpumask_var_t started;

		/* it's true when current open file is snapshot */
		bool snapshot;
		/* All new field here will be zeroed out in pipe_read */
		};

		enum trace_iter_flags {

kernel/trace/trace.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -4151,6 +4151,7 @@ waitagain:
		memset(&iter->seq, 0,
		sizeof(struct trace_iterator) -
		offsetof(struct trace_iterator, seq));
		cpumask_clear(iter->started);
		iter->pos = -1;

		trace_event_read_lock();

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