jerpelea opened a new pull request, #19650:
URL: https://github.com/apache/nuttx/pull/19650

   ## Summary
   
   A task does not necessarily own an address environment.  tcb->addrenv_own is 
set only by addrenv_attach(), which is reached only from addrenv_allocate(); a 
kernel thread never allocates one, and in a protected build nothing does -- 
there is a single address space for the whole system and the architecture's 
up_addrenv_*() are stubs.  addrenv_own is then NULL for every task, always.
   
   That a task may have no address environment is already an expected state. 
addrenv_switch() returns OK when tcb->addrenv_curr is NULL and addrenv_drop() 
returns early, and every caller of addrenv_select() checks addrenv_own != NULL 
before calling in:  nxsched_get_stateinfo(), nxtask_argvstr(), proc_groupenv() 
and the arm, arm64, risc-v and tricore up_check_tcbstack().
   
   addrenv_take() and addrenv_give() are the only two that dereference 
unconditionally.  addrenv_join() calls addrenv_take(ptcb->addrenv_own) without 
a check, so pthread_create() faults on &((struct addrenv_s *)NULL)->refs 
whenever the calling task has no address environment.  With 
CONFIG_DEBUG_ASSERTIONS off the same access silently corrupts low memory 
instead.
   
   Handle NULL in both, the way the rest of the file already does. 
addrenv_give() returns a non-zero count for the NULL case so that callers never 
conclude an absent address environment has become unreferenced and should be 
destroyed.
   
   ## Impact
   
   RELEASE
   
   ## Testing
   
   CI


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