Re: [PATCH 1/2] Fix memory leak in __sbitmap_for_each_set function

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On Fri, Mar 11, 2022 at 4:54 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx> wrote:
Hi Lianbo,

-----Original Message-----
> This reminds me, if parse_line() or dump_struct_member() fails, is there a potential risk of memory leaks
> in the dump_struct_members()?
>
> file: sbitmap.c
> 432 static void dump_struct_members(const char *s, ulong addr, unsigned radix)
> 433 {
> 434         int i, argc;
> 435         char *p1, *p2;
> 436         char *structname, *members;
> 437         char *arglist[MAXARGS];
> 438
> 439         structname = GETBUF(strlen(s) + 1);
> 440         members = GETBUF(strlen(s) + 1);
> 441
> 442         strcpy(structname, s);
> 443         p1 = strstr(structname, ".") + 1;
> 444
> 445         p2 = strstr(s, ".") + 1;
> 446         strcpy(members, p2);
> 447         replace_string(members, ",", ' ');
> 448         argc = parse_line(members, arglist);
> 449
> 450         for (i = 0; i < argc; i++) {
> 451                 *p1 = NULLCHAR;
> 452                 strcat(structname, arglist[i]);
> 453                 dump_struct_member(structname, addr, radix);
> 454         }
> 455
> 456         FREEBUF(structname);
> 457         FREEBUF(members);
> 458 }
>
>
> I noticed that the parse_line() has a return value, but the dump_struct_member() has no return value, is
> there a good way to avoid the potential risks? Or leave it there?
>
> BTW: I saw the similar issues in tools.c

um, the fact is, all buffers that GETBUF() allocates will be freed automatically
after the last command execution in free_all_bufs():

main_loop
  while (TRUE) {
    process_command_line
      restore_sanity
        free_all_bufs <<--
    exec_command
  }

so to free all buffers is better coding practice and has several pros if you can,
but it's not necessary to work too hard for it.

OK, let's leave it there.  The other changes look good to me. Thanks.

For the patchset:
Acked-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
 
Thanks,
Kazu


>
> Thanks.
> Lianbo
>
>
>       @@ -272,7 +272,7 @@ static void __sbitmap_for_each_set(const struct sbitmap_context *sc,
>                               if (nr >= depth)
>                                       break;
>                               if (!fn((index << sc->shift) + nr, data))
>       -                               return;
>       +                               goto exit;
>
>                               nr++;
>                       }
>       @@ -282,6 +282,7 @@ next:
>                               index = 0;
>               }
>
>       +exit:
>               FREEBUF(sbitmap_word_buf);
>        }
>
>       --
>       2.25.1
>

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