tracing: Check if tracing is enabled in trace_puts()

commit 3132e107d608f8753240d82d61303c500fd515b4 upstream.

If trace_puts() is used very early in boot up, it can crash the machine
if it is called before the ring buffer is allocated. If a trace_printk()
is used with no arguments, then it will be converted into a trace_puts()
and suffer the same fate.

Fixes: 09ae72348ecc "tracing: Add trace_puts() for even faster trace_printk() tracing"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b7f5471ae51898f0f409a3124a6a0faf0c4075f7..6dbdf277c8fedf308030cafc9e2ec66e14a31d0e 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -424,6 +424,9 @@ int __trace_puts(unsigned long ip, const char *str, int size)
        unsigned long irq_flags;
        int alloc;
 
+       if (unlikely(tracing_selftest_running || tracing_disabled))
+               return 0;
+
        alloc = sizeof(*entry) + size + 2; /* possible \n added */
 
        local_save_flags(irq_flags);
@@ -464,6 +467,9 @@ int __trace_bputs(unsigned long ip, const char *str)
        unsigned long irq_flags;
        int size = sizeof(struct bputs_entry);
 
+       if (unlikely(tracing_selftest_running || tracing_disabled))
+               return 0;
+
        local_save_flags(irq_flags);
        buffer = global_trace.trace_buffer.buffer;
        event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,