package/network/utils/iptables/patches/070-extensions-string-Review-parse_string-function.patch

   1 From da5b32fb4656ab69fe1156eb7e36c7c961839e8a Mon Sep 17 00:00:00 2001
   2 From: Phil Sutter <phil@nwl.cc>
   3 Date: Wed, 8 Jun 2022 13:45:13 +0200
   4 Subject: [PATCH] extensions: string: Review parse_string() function
   5
   6 * Compare against sizeof(info->pattern) which is more clear than having
   7   to know that this buffer is of size XT_STRING_MAX_PATTERN_SIZE
   8
   9 * Invert the check and error early to reduce indenting
  10
  11 * Pass info->patlen to memcpy() to avoid reading past end of 's'
  12
  13 Signed-off-by: Phil Sutter <phil@nwl.cc>
  14 ---
  15  extensions/libxt_string.c | 13 ++++++-------
  16  1 file changed, 6 insertions(+), 7 deletions(-)
  17
  18 --- a/extensions/libxt_string.c
  19 +++ b/extensions/libxt_string.c
  20 @@ -78,14 +78,13 @@ static void string_init(struct xt_entry_
  21
  22  static void
  23  parse_string(const char *s, struct xt_string_info *info)
  24 -{
  25 +{
  26         /* xt_string does not need \0 at the end of the pattern */
  27 -       if (strlen(s) <= XT_STRING_MAX_PATTERN_SIZE) {
  28 -               memcpy(info->pattern, s, XT_STRING_MAX_PATTERN_SIZE);
  29 -               info->patlen = strnlen(s, XT_STRING_MAX_PATTERN_SIZE);
  30 -               return;
  31 -       }
  32 -       xtables_error(PARAMETER_PROBLEM, "STRING too long \"%s\"", s);
  33 +       if (strlen(s) > sizeof(info->pattern))
  34 +               xtables_error(PARAMETER_PROBLEM, "STRING too long \"%s\"", s);
  35 +
  36 +       info->patlen = strnlen(s, sizeof(info->pattern));
  37 +       memcpy(info->pattern, s, info->patlen);
  38  }
  39
  40  static void