Valgrind "Conditional jump or move depends on uninitialised value(s)" Error

Question

I am getting many errors with valgrind saying "Conditional jump or move depends on uninitialized value(s)".

Below is the one of the blocks. All of them are similar:

vasm_sourceline_info_t* line = asmState->firstLine;
if (line == NULL) return;
while ((line = line->next) != NULL)
{
   printf ("[%s(%i)] %s\n", line->fileName, line->lineNumber, line->data);
}

The error itself is on the while() line. vasm_sourceline_info is a doubly linked list structure. The code ~works~ but this error is worrying. Is there something else in code stomping on memory, or is the above function flawed in some way?

Answer 1

Compile with optimizations OFF (-O0). Run valgrind with --track-origins=yes to determine the source of the errors. See here for more.

Answer 2

There's nothing wrong with the code per se, but if one of the lines' next field has not been initialized (presumably the last line's next field), that would explain the message.