From 7714d3b377f65ec49f2e5268107976797e92ea2f Mon Sep 17 00:00:00 2001 From: Andrew Vagin Date: Fri, 2 Aug 2013 21:16:43 +0400 Subject: [PATCH] tracing: Fix fields of struct trace_iterator that are zeroed by mistake [ Upstream commit ed5467da0e369e65b247b99eb6403cb79172bcda ] 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 Signed-off-by: Steven Rostedt --- include/linux/ftrace_event.h | 4 +++- kernel/trace/trace.c | 1 + 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 59d3ef1..217b3c2 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -71,6 +71,8 @@ struct trace_iterator { /* trace_seq for __print_flags() and __print_symbolic() etc. */ struct trace_seq tmp_seq; + cpumask_var_t started; + /* The below is zeroed out in pipe_read */ struct trace_seq seq; struct trace_entry *ent; @@ -82,7 +84,7 @@ struct trace_iterator { loff_t pos; long idx; - cpumask_var_t started; + /* All new field here will be zeroed out in pipe_read */ }; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 91b8e9a..f15b21a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3245,6 +3245,7 @@ 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(); -- 1.8.3.1