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Re: CPPCheck found 24 high risk bugs in Git v.1.8.3.4

From
Jeff King <peff@peff.net>
Date
Aug 20, 2013, 14:33 UTC
Message-ID
<20130820143306.GC32370@sigill.intra.peff.net>
In-Reply-To
<CABPQNSZidMv4MEW+SqVm94pX4szw9QW8LFWsvBTOXYH7ezzycw@mail.gmail.com>
On Tue, Aug 20, 2013 at 01:15:02AM +0200, Erik Faye-Lund wrote:
Show 6 quoted lines
> This one seems real, although it's quite theoretical. It should only happen
> in cases where the log-message contains "%1", the initial malloc passed and
> reallocing two more bytes failed.
> 
> However, what's much more of a disaster: "pos" is used after the call to
> realloc might have moved the memory!
Yeah, agreed on both counts.
Show 26 quoted lines
> I guess something like this should fix both issues. Sorry about the
> lack of indentation, it seems Gmail has regressed, and the old compose
> mode is somehow gone... (also sorry for triple-posting to some of you,
> Gmail seems particularly broken today)
> 
> diff --git a/compat/win32/syslog.c b/compat/win32/syslog.c
> index d015e43..0641f4e 100644
> --- a/compat/win32/syslog.c
> +++ b/compat/win32/syslog.c
> @@ -43,11 +43,14 @@ void syslog(int priority, const char *fmt, ...)
>   va_end(ap);
> 
>   while ((pos = strstr(str, "%1")) != NULL) {
> - str = realloc(str, ++str_len + 1);
> - if (!str) {
> + char *tmp = realloc(str, ++str_len + 1);
> + if (!tmp) {
>   warning("realloc failed: '%s'", strerror(errno));
> + free(str);
>   return;
>   }
> + pos = tmp + (pos - str);
> + str = tmp;
>   memmove(pos + 2, pos + 1, strlen(pos));
>   pos[1] = ' ';
>   }

Yes, that looks like the right solution. You could also convert "pos" to an integer index rather than a pointer (but then you end up adding it it to the pointer in the memmove call, which is probably just as ugly).

-Peff
Previous: Erik Faye-LundNext: Andreas Schwab
Message 8 of 18 in “CPPCheck found 24 high risk bugs in Git v.1.8.3.4”
  1. Koch, Rick (Subcontractor)Aug 19, 2013
  2. Philip OakleyAug 19, 2013
  3. Jeff KingAug 19, 2013
  4. Junio C HamanoAug 19, 2013
  5. Johan HerlandAug 19, 2013
  6. Philip OakleyAug 19, 2013
  7. Erik Faye-LundAug 19, 2013
  8. Jeff KingAug 20, 2013
  9. Andreas SchwabAug 20, 2013
  10. René ScharfeAug 20, 2013
  11. Erik Faye-LundAug 20, 2013
  12. Erik Faye-LundAug 20, 2013
  13. Andreas SchwabAug 20, 2013
  14. Junio C HamanoAug 20, 2013
  15. Erik Faye-LundAug 21, 2013
  16. Stefan BellerAug 19, 2013
  17. Philip OakleyAug 19, 2013
  18. Philip OakleyAug 23, 2013

Read the whole thread, see it on lore, or plain text.

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