target/linux/bcm27xx/patches-5.4/950-0479-drm-modes-parse_cmdline-Fix-possible-reference-past-.patch

   1 From fade8b3cf37785297b4f8a9bbd13ab107208af5a Mon Sep 17 00:00:00 2001
   2 From: Hans de Goede <hdegoede@redhat.com>
   3 Date: Mon, 18 Nov 2019 16:51:22 +0100
   4 Subject: [PATCH] drm/modes: parse_cmdline: Fix possible reference past
   5  end of string
   6
   7 Commit 8582e244e5fe72d2e9ace186fa8f3ed3bb4122e1 upstream.
   8
   9 Before this commit, if the last option of a video=... option is for
  10 example "rotate" without a "=<value>" after it then delim will point to
  11 the terminating 0 of the string, and value which is sets to <delim + 1>
  12 will point one position past the end of the string.
  13
  14 This commit fixes this by enforcing that the contents of delim equals '='
  15 as it should be for options which take a value, this check is done in a
  16 new drm_mode_parse_cmdline_int helper function which factors out the
  17 common integer parsing code for all the options which take an int.
  18
  19 Acked-by: Maxime Ripard <mripard@kernel.org>
  20 Signed-off-by: Hans de Goede <hdegoede@redhat.com>
  21 Link: https://patchwork.freedesktop.org/patch/msgid/20191118155134.30468-1-hdegoede@redhat.com
  22 ---
  23  drivers/gpu/drm/drm_modes.c | 68 ++++++++++++++++---------------------
  24  1 file changed, 30 insertions(+), 38 deletions(-)
  25
  26 --- a/drivers/gpu/drm/drm_modes.c
  27 +++ b/drivers/gpu/drm/drm_modes.c
  28 @@ -1568,11 +1568,34 @@ static int drm_mode_parse_cmdline_res_mo
  29         return 0;
  30  }
  31
  32 +static int drm_mode_parse_cmdline_int(const char *delim, unsigned int *int_ret)
  33 +{
  34 +       const char *value;
  35 +       char *endp;
  36 +
  37 +       /*
  38 +        * delim must point to the '=', otherwise it is a syntax error and
  39 +        * if delim points to the terminating zero, then delim + 1 wil point
  40 +        * past the end of the string.
  41 +        */
  42 +       if (*delim != '=')
  43 +               return -EINVAL;
  44 +
  45 +       value = delim + 1;
  46 +       *int_ret = simple_strtol(value, &endp, 10);
  47 +
  48 +       /* Make sure we have parsed something */
  49 +       if (endp == value)
  50 +               return -EINVAL;
  51 +
  52 +       return 0;
  53 +}
  54 +
  55  static int drm_mode_parse_cmdline_options(char *str, size_t len,
  56                                           const struct drm_connector *connector,
  57                                           struct drm_cmdline_mode *mode)
  58  {
  59 -       unsigned int rotation = 0;
  60 +       unsigned int deg, margin, rotation = 0;
  61         char *sep = str;
  62
  63         while ((sep = strchr(sep, ','))) {
  64 @@ -1588,13 +1611,7 @@ static int drm_mode_parse_cmdline_option
  65                 }
  66
  67                 if (!strncmp(option, "rotate", delim - option)) {
  68 -                       const char *value = delim + 1;
  69 -                       unsigned int deg;
  70 -
  71 -                       deg = simple_strtol(value, &sep, 10);
  72 -
  73 -                       /* Make sure we have parsed something */
  74 -                       if (sep == value)
  75 +                       if (drm_mode_parse_cmdline_int(delim, &deg))
  76                                 return -EINVAL;
  77
  78                         switch (deg) {
  79 @@ -1619,57 +1636,32 @@ static int drm_mode_parse_cmdline_option
  80                         }
  81                 } else if (!strncmp(option, "reflect_x", delim - option)) {
  82                         rotation |= DRM_MODE_REFLECT_X;
  83 -                       sep = delim;
  84                 } else if (!strncmp(option, "reflect_y", delim - option)) {
  85                         rotation |= DRM_MODE_REFLECT_Y;
  86 -                       sep = delim;
  87                 } else if (!strncmp(option, "margin_right", delim - option)) {
  88 -                       const char *value = delim + 1;
  89 -                       unsigned int margin;
  90 -
  91 -                       margin = simple_strtol(value, &sep, 10);
  92 -
  93 -                       /* Make sure we have parsed something */
  94 -                       if (sep == value)
  95 +                       if (drm_mode_parse_cmdline_int(delim, &margin))
  96                                 return -EINVAL;
  97
  98                         mode->tv_margins.right = margin;
  99                 } else if (!strncmp(option, "margin_left", delim - option)) {
 100 -                       const char *value = delim + 1;
 101 -                       unsigned int margin;
 102 -
 103 -                       margin = simple_strtol(value, &sep, 10);
 104 -
 105 -                       /* Make sure we have parsed something */
 106 -                       if (sep == value)
 107 +                       if (drm_mode_parse_cmdline_int(delim, &margin))
 108                                 return -EINVAL;
 109
 110                         mode->tv_margins.left = margin;
 111                 } else if (!strncmp(option, "margin_top", delim - option)) {
 112 -                       const char *value = delim + 1;
 113 -                       unsigned int margin;
 114 -
 115 -                       margin = simple_strtol(value, &sep, 10);
 116 -
 117 -                       /* Make sure we have parsed something */
 118 -                       if (sep == value)
 119 +                       if (drm_mode_parse_cmdline_int(delim, &margin))
 120                                 return -EINVAL;
 121
 122                         mode->tv_margins.top = margin;
 123                 } else if (!strncmp(option, "margin_bottom", delim - option)) {
 124 -                       const char *value = delim + 1;
 125 -                       unsigned int margin;
 126 -
 127 -                       margin = simple_strtol(value, &sep, 10);
 128 -
 129 -                       /* Make sure we have parsed something */
 130 -                       if (sep == value)
 131 +                       if (drm_mode_parse_cmdline_int(delim, &margin))
 132                                 return -EINVAL;
 133
 134                         mode->tv_margins.bottom = margin;
 135                 } else {
 136                         return -EINVAL;
 137                 }
 138 +               sep = delim;
 139         }
 140
 141         if (!(rotation & DRM_MODE_ROTATE_MASK))