[Nasm-bugs] [Bug 3392474] New: Endless while loop inside assemble_file function

[noreply-nasm at gorcunov.org]

https://bugzilla.nasm.us/show_bug.cgi?id=3392474

            Bug ID: 3392474
           Summary: Endless while loop inside assemble_file function
           Product: NASM
           Version: 2.14 (development)
          Hardware: All
                OS: All
            Status: OPEN
          Severity: normal
          Priority: Medium
         Component: Assembler
          Assignee: nobody at nasm.us
          Reporter: mudongliangabcd at gmail.com
                CC: gorcunov at gmail.com, hpa at zytor.com, nasm-bugs at nasm.us
     Obtained from: Build from source archive using configure

Created attachment 411635
  --> https://bugzilla.nasm.us/attachment.cgi?id=411635&action=edit
PoC to make nasm hang

With crafted file, the following while loop never stops as line will never be
NULL.

1233            while ((line = preproc->getline())) {
1234                globallineno++;
...

In pp_getline(preproc->getline) function, the last assignment is 

5215                    line = detoken(tline, true);
...

In detoken function, line is assigned by 

1308        p = line = nasm_malloc(len + 1);

>From nasm_malloc implementation, it will never return NULL.

53      void *nasm_calloc(size_t size, size_t nelem)
54      {
55          void *p = calloc(size, nelem);                                     
                                                          56          if (!p)  
                                                                               
             57              nasm_fatal(ERR_NOFILE, "out of memory");          
                                                                               
     58          return p;                                                     
                                          59      }                            
                                                                   60

So the while loop inside assemble_file function will never stop.

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