screen/trunk/CVE-2021-26937.patch

   1 Description: [CVE-2021-26937] Fix out of bounds array access
   2 Author: Michael Schröder <mls@suse.de>
   3 Bug-Debian: https://bugs.debian.org/982435
   4 Bug: https://savannah.gnu.org/bugs/?60030
   5 Bug: https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html
   6 Bug-OSS-Security: https://www.openwall.com/lists/oss-security/2021/02/09/3
   7 Origin: https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00010.html
   8
   9 --- a/encoding.c
  10 +++ b/encoding.c
  11 @@ -43,7 +43,7 @@
  12  # ifdef UTF8
  13  static int   recode_char __P((int, int, int));
  14  static int   recode_char_to_encoding __P((int, int));
  15 -static void  comb_tofront __P((int, int));
  16 +static void  comb_tofront __P((int));
  17  #  ifdef DW_CHARS
  18  static int   recode_char_dw __P((int, int *, int, int));
  19  static int   recode_char_dw_to_encoding __P((int, int *, int));
  20 @@ -1263,6 +1263,8 @@
  21      {0x30000, 0x3FFFD},
  22    };
  23
  24 +  if (c >= 0xdf00 && c <= 0xdfff)
  25 +    return 1;          /* dw combining sequence */
  26    return ((bisearch(c, wide, sizeof(wide) / sizeof(struct interval) - 1)) ||
  27            (cjkwidth &&
  28             bisearch(c, ambiguous,
  29 @@ -1330,11 +1332,12 @@
  30  }
  31
  32  static void
  33 -comb_tofront(root, i)
  34 -int root, i;
  35 +comb_tofront(i)
  36 +int i;
  37  {
  38    for (;;)
  39      {
  40 +      int root = i >= 0x700 ? 0x801 : 0x800;
  41        debug1("bring to front: %x\n", i);
  42        combchars[combchars[i]->prev]->next = combchars[i]->next;
  43        combchars[combchars[i]->next]->prev = combchars[i]->prev;
  44 @@ -1396,9 +1399,9 @@
  45      {
  46        /* full, recycle old entry */
  47        if (c1 >= 0xd800 && c1 < 0xe000)
  48 -        comb_tofront(root, c1 - 0xd800);
  49 +        comb_tofront(c1 - 0xd800);
  50        i = combchars[root]->prev;
  51 -      if (c1 == i + 0xd800)
  52 +      if (i == 0x800 || i == 0x801 || c1 == i + 0xd800)
  53         {
  54           /* completely full, can't recycle */
  55           debug("utf8_handle_comp: completely full!\n");
  56 @@ -1422,7 +1425,7 @@
  57    mc->font  = (i >> 8) + 0xd8;
  58    mc->fontx = 0;
  59    debug3("combinig char %x %x -> %x\n", c1, c, i + 0xd800);
  60 -  comb_tofront(root, i);
  61 +  comb_tofront(i);
  62  }
  63
  64  #else /* !UTF8 */