Messages in this thread | | | Date | Fri, 17 Jun 2016 12:38:41 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] tracing: Add *iter check for NULL |
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On Wed, 1 Jun 2016 16:31:10 +0800 zhengjun.xing@intel.com wrote:
> From: xingzhen <zhengjun.xing@intel.com> > > 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 <zhengjun.xing@intel.com> > --- > 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); > } >
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