Hi Bruno, On Sonntag, 2. Juli 2017 14:00:27 CEST Bruno Haible wrote: > > In code that I am responsible for, > > especially complex code as glob(), I also set pointers to NULL after > > free() or when assigning/moving to another variable. > > Such a coding style does not help. What you need is to reduce the > complexity, either by introducing inline functions, or by at least reducing > the scope of the variables in the big function. > > The only situations where "set pointers to NULL after free()" is useful are: > - when you're dealing with global variables or heap-allocated struct > members (or class members in C++), or > - when there is a (conservative) garbage collector around.
What I meant (in general) is the avoidance of 'use after free' [1] issues. Not leaving around dangling pointers avoids this, so erroneous code is more unlikely to become a security issue (it's just a segmentation fault then). In glob() the code is not resetting the dirname memory policy flag when 'dirname' is stuffed into another variable. No doing so can easily lead to either a double free and/or a use after free. Regards, Tim [1] https://www.owasp.org/index.php/Using_freed_memory
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