On Wed, 1 Jun 2016 16:31:10 +0800 [email protected] wrote: > From: xingzhen <[email protected]> > > 3debb0a9ddb adding a "__used" to the variable in the > __trace_printk_fmt section. Sometimes it will cause > *iter to be NULL, then strcmp in lookup_format and > strcpy in hold_module_trace_bprintk_format will panic.
Could you show an example of this happening? > > Signed-off-by: xingzhen <[email protected]> > --- > kernel/trace/trace_printk.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c > index f96f038..82ecfb5 100644 > --- a/kernel/trace/trace_printk.c > +++ b/kernel/trace/trace_printk.c > @@ -55,6 +55,8 @@ void hold_module_trace_bprintk_format(const char **start, > const char **end) > > mutex_lock(&btrace_mutex); > for (iter = start; iter < end; iter++) { > + if (!*iter) > + goto err; > struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter); First, you can't place logic before a declaration. Not all compilers will allow that. Also, do we really want to error on this or just skip it? Because it will miss out on all other trace_printks in the module. -- Steve > if (tb_fmt) { > *iter = tb_fmt->fmt; > @@ -75,6 +77,7 @@ void hold_module_trace_bprintk_format(const char **start, > const char **end) > *iter = fmt; > > } > +err: > mutex_unlock(&btrace_mutex); > } >
