git.ipfire.org Git - thirdparty/openembedded/openembedded-core-contrib.git/blob

   1 From 68a09a74f6d726d79709847f3671c0a08e4fb5a0 Mon Sep 17 00:00:00 2001
   2 From: Colin Watson <cjwatson@debian.org>
   3 Date: Sat, 25 Jul 2020 12:15:37 +0100
   4 Subject: [PATCH 9/9] linux: Fix integer overflows in initrd size handling
   5
   6 These could be triggered by a crafted filesystem with very large files.
   7
   8 Fixes: CVE-2020-15707
   9
  10 Signed-off-by: Colin Watson <cjwatson@debian.org>
  11 Reviewed-by: Jan Setje-Eilers <jan.setjeeilers@oracle.com>
  12 Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
  13
  14 Upstream-Status: Backport
  15 CVE: CVE-2020-15707
  16
  17 Reference to upstream patch:
  18 https://git.savannah.gnu.org/cgit/grub.git/commit/?id=e7b8856f8be3292afdb38d2e8c70ad8d62a61e10
  19
  20 Signed-off-by: Yongxin Liu <yongxin.liu@windriver.com>
  21 ---
  22  grub-core/loader/linux.c | 74 +++++++++++++++++++++++++++++++++++-------------
  23  1 file changed, 54 insertions(+), 20 deletions(-)
  24
  25 diff --git a/grub-core/loader/linux.c b/grub-core/loader/linux.c
  26 index 471b214..8c8565a 100644
  27 --- a/grub-core/loader/linux.c
  28 +++ b/grub-core/loader/linux.c
  29 @@ -4,6 +4,7 @@
  30  #include <grub/misc.h>
  31  #include <grub/file.h>
  32  #include <grub/mm.h>
  33 +#include <grub/safemath.h>
  34
  35  struct newc_head
  36  {
  37 @@ -98,13 +99,13 @@ free_dir (struct dir *root)
  38    grub_free (root);
  39  }
  40
  41 -static grub_size_t
  42 +static grub_err_t
  43  insert_dir (const char *name, struct dir **root,
  44 -           grub_uint8_t *ptr)
  45 +           grub_uint8_t *ptr, grub_size_t *size)
  46  {
  47    struct dir *cur, **head = root;
  48    const char *cb, *ce = name;
  49 -  grub_size_t size = 0;
  50 +  *size = 0;
  51    while (1)
  52      {
  53        for (cb = ce; *cb == '/'; cb++);
  54 @@ -130,14 +131,22 @@ insert_dir (const char *name, struct dir **root,
  55               ptr = make_header (ptr, name, ce - name,
  56                                  040777, 0);
  57             }
  58 -         size += ALIGN_UP ((ce - (char *) name)
  59 -                           + sizeof (struct newc_head), 4);
  60 +         if (grub_add (*size,
  61 +                       ALIGN_UP ((ce - (char *) name)
  62 +                                 + sizeof (struct newc_head), 4),
  63 +                       size))
  64 +           {
  65 +             grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow is detected"));
  66 +             grub_free (n->name);
  67 +             grub_free (n);
  68 +             return grub_errno;
  69 +           }
  70           *head = n;
  71           cur = n;
  72         }
  73        root = &cur->next;
  74      }
  75 -  return size;
  76 +  return GRUB_ERR_NONE;
  77  }
  78
  79  grub_err_t
  80 @@ -173,26 +182,33 @@ grub_initrd_init (int argc, char *argv[],
  81           eptr = grub_strchr (ptr, ':');
  82           if (eptr)
  83             {
  84 +             grub_size_t dir_size, name_len;
  85 +
  86               initrd_ctx->components[i].newc_name = grub_strndup (ptr, eptr - ptr);
  87 -             if (!initrd_ctx->components[i].newc_name)
  88 +             if (!initrd_ctx->components[i].newc_name ||
  89 +                 insert_dir (initrd_ctx->components[i].newc_name, &root, 0,
  90 +                             &dir_size))
  91                 {
  92                   grub_initrd_close (initrd_ctx);
  93                   return grub_errno;
  94                 }
  95 -             initrd_ctx->size
  96 -               += ALIGN_UP (sizeof (struct newc_head)
  97 -                           + grub_strlen (initrd_ctx->components[i].newc_name),
  98 -                            4);
  99 -             initrd_ctx->size += insert_dir (initrd_ctx->components[i].newc_name,
 100 -                                             &root, 0);
 101 +             name_len = grub_strlen (initrd_ctx->components[i].newc_name);
 102 +             if (grub_add (initrd_ctx->size,
 103 +                           ALIGN_UP (sizeof (struct newc_head) + name_len, 4),
 104 +                           &initrd_ctx->size) ||
 105 +                 grub_add (initrd_ctx->size, dir_size, &initrd_ctx->size))
 106 +               goto overflow;
 107               newc = 1;
 108               fname = eptr + 1;
 109             }
 110         }
 111        else if (newc)
 112         {
 113 -         initrd_ctx->size += ALIGN_UP (sizeof (struct newc_head)
 114 -                                       + sizeof ("TRAILER!!!") - 1, 4);
 115 +         if (grub_add (initrd_ctx->size,
 116 +                       ALIGN_UP (sizeof (struct newc_head)
 117 +                                 + sizeof ("TRAILER!!!") - 1, 4),
 118 +                       &initrd_ctx->size))
 119 +           goto overflow;
 120           free_dir (root);
 121           root = 0;
 122           newc = 0;
 123 @@ -208,19 +224,29 @@ grub_initrd_init (int argc, char *argv[],
 124        initrd_ctx->nfiles++;
 125        initrd_ctx->components[i].size
 126         = grub_file_size (initrd_ctx->components[i].file);
 127 -      initrd_ctx->size += initrd_ctx->components[i].size;
 128 +      if (grub_add (initrd_ctx->size, initrd_ctx->components[i].size,
 129 +                   &initrd_ctx->size))
 130 +       goto overflow;
 131      }
 132
 133    if (newc)
 134      {
 135        initrd_ctx->size = ALIGN_UP (initrd_ctx->size, 4);
 136 -      initrd_ctx->size += ALIGN_UP (sizeof (struct newc_head)
 137 -                                   + sizeof ("TRAILER!!!") - 1, 4);
 138 +      if (grub_add (initrd_ctx->size,
 139 +                   ALIGN_UP (sizeof (struct newc_head)
 140 +                             + sizeof ("TRAILER!!!") - 1, 4),
 141 +                   &initrd_ctx->size))
 142 +       goto overflow;
 143        free_dir (root);
 144        root = 0;
 145      }
 146
 147    return GRUB_ERR_NONE;
 148 +
 149 + overflow:
 150 +  free_dir (root);
 151 +  grub_initrd_close (initrd_ctx);
 152 +  return grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow is detected"));
 153  }
 154
 155  grub_size_t
 156 @@ -261,8 +287,16 @@ grub_initrd_load (struct grub_linux_initrd_context *initrd_ctx,
 157
 158        if (initrd_ctx->components[i].newc_name)
 159         {
 160 -         ptr += insert_dir (initrd_ctx->components[i].newc_name,
 161 -                            &root, ptr);
 162 +         grub_size_t dir_size;
 163 +
 164 +         if (insert_dir (initrd_ctx->components[i].newc_name, &root, ptr,
 165 +                         &dir_size))
 166 +           {
 167 +             free_dir (root);
 168 +             grub_initrd_close (initrd_ctx);
 169 +             return grub_errno;
 170 +           }
 171 +         ptr += dir_size;
 172           ptr = make_header (ptr, initrd_ctx->components[i].newc_name,
 173                              grub_strlen (initrd_ctx->components[i].newc_name),
 174                              0100777,
 175 --
 176 2.14.4
 177