Freeing memory allocated in the inferior

Simon Marchi
Mon Feb 20 17:58:00 GMT 2017

On 2017-02-20 05:11, Matthew Malcomson wrote:
> Hello,
> I've just been reading the code, and was hoping someone could help me
> understand something.
> It seems that memory allocated in the inferior (with
> `value_allocate_space_in_inferior()` is never freed, even when the gdb
> process exits/detaches.
> Is this true (i.e. have I missed something)?
> I found an old comment on an old bug that implies this is correct
>, and the
> pointer appears to remain valid in the inferior over a lot of
> allocation after detaching, but neither of those are particularly
> conclusive.
> If so, why is this?
> I can see it would be difficult to know when to free them during
> execution, because the user may simply remember the pointer address
> the variable is stored and attempt to use it, but what about storing
> the allocations on a data structure somewhere, and freeing them when
> gdb is closing/detaching?
> I doubt many users are remembering pointer addresses after having
> detached and attached again to a process, but I guess there could be
> an extra `set` parameter introduced if this were the case.

The memory could be needed even after gdb exits/detaches.  Consider the 
case where you use gdb to insert a string in some data structure and 
detach from the inferior to let it run freely.  If gdb frees the memory 
containing the string, the data structure will contain an invalid 

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