git.openwrt.org Git - openwrt/staging/dangole.git/blob

   1 From ab51d587bb9b229b1fade1afd02e1574c1ba5c76 Mon Sep 17 00:00:00 2001
   2 From: Lukas Czerner <lczerner@redhat.com>
   3 Date: Thu, 21 Apr 2022 19:31:48 +0200
   4 Subject: libext2fs: add sanity check to extent manipulation
   5
   6 It is possible to have a corrupted extent tree in such a way that a leaf
   7 node contains zero extents in it. Currently if that happens and we try
   8 to traverse the tree we can end up accessing wrong data, or possibly
   9 even uninitialized memory. Make sure we don't do that.
  10
  11 Additionally make sure that we have a sane number of bytes passed to
  12 memmove() in ext2fs_extent_delete().
  13
  14 Note that e2fsck is currently unable to spot and fix such corruption in
  15 pass1.
  16
  17 Signed-off-by: Lukas Czerner <lczerner@redhat.com>
  18 Reported-by: Nils Bars <nils_bars@t-online.de>
  19 Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=2068113
  20 Addresses: CVE-2022-1304
  21 Addresses-Debian-Bug: #1010263
  22 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  23 ---
  24  lib/ext2fs/extent.c | 8 ++++++++
  25  1 file changed, 8 insertions(+)
  26
  27 --- a/lib/ext2fs/extent.c
  28 +++ b/lib/ext2fs/extent.c
  29 @@ -495,6 +495,10 @@ retry:
  30                         ext2fs_le16_to_cpu(eh->eh_entries);
  31                 newpath->max_entries = ext2fs_le16_to_cpu(eh->eh_max);
  32
  33 +               /* Make sure there is at least one extent present */
  34 +               if (newpath->left <= 0)
  35 +                       return EXT2_ET_EXTENT_NO_DOWN;
  36 +
  37                 if (path->left > 0) {
  38                         ix++;
  39                         newpath->end_blk = ext2fs_le32_to_cpu(ix->ei_block);
  40 @@ -1630,6 +1634,10 @@ errcode_t ext2fs_extent_delete(ext2_exte
  41
  42         cp = path->curr;
  43
  44 +       /* Sanity check before memmove() */
  45 +       if (path->left < 0)
  46 +               return EXT2_ET_EXTENT_LEAF_BAD;
  47 +
  48         if (path->left) {
  49                 memmove(cp, cp + sizeof(struct ext3_extent_idx),
  50                         path->left * sizeof(struct ext3_extent_idx));