Re: [Valgrind-users] Conditional jump or move in printf

[John R. <jr...@bi...>]

> 6:     sprintf(lMsg, "%i%i%i%i", 1, 2, 3, 4);
> 7:     printf("%s", lMsg);

> memcheck with Valgrind 3.8.1 complains about:
> 
> ==28037== Conditional jump or move depends on uninitialised value(s)
> ==28037==    at 0x41EB419: ??? (in /lib/tls/i686/cmov/libc-2.11.1.so)
> ==28037==    by 0x41BF2BF: printf (in /lib/tls/i686/cmov/libc-2.11.1.so)
> ==28037==    by 0x80485B6: main (test.cpp:7)
> ==28037==  Uninitialised value was created by a stack allocation
> ==28037==    at 0x804855A: main (test.cpp:4)
> 
> I'm fairly new to Valgrind and I can't figure out what's wrong - but it feels like I am missing something obvious :) Any ideas?

The suspect code is in a subroutine that is called by printf, and is inside libc-2.11.1.so.
It's probably the equivalent of strlen() applied to "1234", and which uses
word-wide operations on the terminating "\0???" where the '?' are uninit bytes.
Therefore this particular complaint is a "false positive" that you should ignore.

libc-2.11 is about three years old; 2.17 is current.  The complaint above
does not arise with 2.17.  Have you considered upgrading?

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