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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>
This commit is contained in:
Andrew Vagin 2013-08-02 21:16:43 +04:00 committed by Steven Rostedt
parent c6c2401d8b
commit ed5467da0e
2 changed files with 7 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/linux/ftrace_event.h
View File

@ -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 {

1
kernel/trace/trace.c
View File

@ -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();