From 4ca530852346be239b7c19e7bec5d2b78855bebe Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 16 Mar 2009 19:20:15 -0400 Subject: tracing: protect reader of cmdline output Impact: fix to one cause of incorrect comm outputs in trace The spinlock only protected the creation of a comm <=> pid pair. But it was possible that a reader could look up a pid, and get the wrong comm because it had no locking. This also required changing trace_find_cmdline to copy the comm cache and not just send back a pointer to it. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index efe3202c0209..2796bd2b17e4 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -770,25 +770,29 @@ static void trace_save_cmdline(struct task_struct *tsk) __raw_spin_unlock(&trace_cmdline_lock); } -char *trace_find_cmdline(int pid) +void trace_find_cmdline(int pid, char comm[]) { - char *cmdline = "<...>"; unsigned map; - if (!pid) - return ""; + if (!pid) { + strcpy(comm, ""); + return; + } - if (pid > PID_MAX_DEFAULT) - goto out; + if (pid > PID_MAX_DEFAULT) { + strcpy(comm, "<...>"); + return; + } + __raw_spin_lock(&trace_cmdline_lock); map = map_pid_to_cmdline[pid]; if (map >= SAVED_CMDLINES) goto out; - cmdline = saved_cmdlines[map]; + strcpy(comm, saved_cmdlines[map]); out: - return cmdline; + __raw_spin_unlock(&trace_cmdline_lock); } void tracing_record_cmdline(struct task_struct *tsk) -- cgit v1.2.3