Steven Rostedt (Red Hat) bc64a83932 tracing: Handle NULL formats in hold_module_trace_bprintk_format() ... commit 70c8217acd upstream. If a task uses a non constant string for the format parameter in trace_printk(), then the trace_printk_fmt variable is set to NULL. This variable is then saved in the __trace_printk_fmt section. The function hold_module_trace_bprintk_format() checks to see if duplicate formats are used by modules, and reuses them if so (saves them to the list if it is new). But this function calls lookup_format() that does a strcmp() to the value (which is now NULL) and can cause a kernel oops. This wasn't an issue till 3debb0a9dd ("tracing: Fix trace_printk() to print when not using bprintk()") which added "__used" to the trace_printk_fmt variable, and before that, the kernel simply optimized it out (no NULL value was saved). The fix is simply to handle the NULL pointer in lookup_format() and have the caller ignore the value if it was NULL. Link: http://lkml.kernel.org/r/1464769870-18344-1-git-send-email-zhengjun.xing@intel.com Reported-by: xingzhen <zhengjun.xing@intel.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Fixes: 3debb0a9dd ("tracing: Fix trace_printk() to print when not using bprintk()") Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2016-07-27 09:47:32 -07:00
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blktrace.c
bpf_trace.c
ftrace.c
Kconfig
Makefile
power-traces.c
ring_buffer_benchmark.c
ring_buffer.c	ring-buffer: Prevent overflow of size in ring_buffer_resize()	2016-06-01 12:15:49 -07:00
rpm-traces.c
trace_benchmark.c
trace_benchmark.h
trace_branch.c
trace_clock.c
trace_entries.h
trace_event_perf.c
trace_events_filter_test.h
trace_events_filter.c	tracing: Do not have 'comm' filter override event 'comm' field	2016-03-09 15:34:52 -08:00
trace_events_trigger.c
trace_events.c	tracing: Don't display trigger file for events that can't be enabled	2016-05-11 11:21:13 +02:00
trace_export.c
trace_functions_graph.c
trace_functions.c
trace_irqsoff.c	tracing: Have preempt(irqs)off trace preempt disabled functions	2016-04-12 09:08:59 -07:00
trace_kdb.c
trace_kprobe.c
trace_mmiotrace.c
trace_nop.c
trace_output.c
trace_output.h
trace_printk.c	tracing: Handle NULL formats in hold_module_trace_bprintk_format()	2016-07-27 09:47:32 -07:00
trace_probe.c
trace_probe.h
trace_sched_switch.c
trace_sched_wakeup.c
trace_selftest_dynamic.c
trace_selftest.c
trace_seq.c
trace_stack.c
trace_stat.c
trace_stat.h
trace_syscalls.c
trace_uprobe.c
trace.c	tracing: Fix crash from reading trace_pipe with sendfile	2016-04-12 09:08:59 -07:00
trace.h