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From: "wenji dot huang at oracle dot com" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug translator/6979] using $$parms under uprobe probes might result in a uninitialized variable access.
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------- Additional Comments From wenji dot huang at oracle dot com  2009-02-03 07:50 -------
Did some more tests. Seems it will happen on specific probe point combination
with $$parms. Such as,
stap -p4 -vve 'probe kernel.function("proc_reg_llseek"){printf("%s\n",$$parms)}'

But it can pass when executing
stap -p4 -vve 'probe kernel.function("proc_reg_llseek"){printf("%s\n",pp())}'
stap -p4 -vve 'probe kernel.function("proc_register"){printf("%s\n",$$parms)}'

The root cause is the generated incorrect code
       {
         intptr_t s0;
         addr = s0;
       }
It should be like,
       {
        intptr_t s0;
        s0 = fetch_register (5) + -28L;
        addr = s0;
       }

Theses are from loc2c.c::emit_loc_address,
      emit ("%s%*s%s = " STACKFMT ";\n", loc->address.program,
            (indent + 1) * 2, "", target, 0);
In some cases, loc->address.program='\0' cause the error.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6979

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