3.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: "Steven Rostedt (Red Hat)" <rost...@goodmis.org>
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 <rost...@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
kernel/trace/trace.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -435,6 +435,9 @@ int __trace_puts(unsigned long ip, const
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);
@@ -475,6 +478,9 @@ int __trace_bputs(unsigned long ip, cons
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,
--
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