code.ossystems Code Review - openembedded-core.git/blob

   1 From 49d0fe2a14f2a23da2fe299643379b8c1d37df73 Mon Sep 17 00:00:00 2001
   2 From: Theodore Ts'o <tytso@mit.edu>
   3 Date: Fri, 6 Feb 2015 12:46:39 -0500
   4 Subject: [PATCH] libext2fs: fix potential buffer overflow in closefs()
   5
   6 Upstream-Status: Backport
   7 CVE: CVE-2015-1572
   8
   9 The bug fix in f66e6ce4446: "libext2fs: avoid buffer overflow if
  10 s_first_meta_bg is too big" had a typo in the fix for
  11 ext2fs_closefs().  In practice most of the security exposure was from
  12 the openfs path, since this meant if there was a carefully crafted
  13 file system, buffer overrun would be triggered when the file system was
  14 opened.
  15
  16 However, if corrupted file system didn't trip over some corruption
  17 check, and then the file system was modified via tune2fs or debugfs,
  18 such that the superblock was marked dirty and then written out via the
  19 closefs() path, it's possible that the buffer overrun could be
  20 triggered when the file system is closed.
  21
  22 Also clear up a signed vs unsigned warning while we're at it.
  23
  24 Thanks to Nick Kralevich <nnk@google.com> for asking me to look at
  25 compiler warning in the code in question, which led me to notice the
  26 bug in f66e6ce4446.
  27
  28 Addresses: CVE-2015-1572
  29
  30 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  31 ---
  32  lib/ext2fs/closefs.c | 4 ++--
  33  1 file changed, 2 insertions(+), 2 deletions(-)
  34
  35 diff --git a/lib/ext2fs/closefs.c b/lib/ext2fs/closefs.c
  36 index 1f99113..ab5b2fb 100644
  37 --- a/lib/ext2fs/closefs.c
  38 +++ b/lib/ext2fs/closefs.c
  39 @@ -287,7 +287,7 @@ errcode_t ext2fs_flush2(ext2_filsys fs, int flags)
  40         dgrp_t          j;
  41  #endif
  42         char    *group_ptr;
  43 -       int     old_desc_blocks;
  44 +       blk64_t old_desc_blocks;
  45         struct ext2fs_numeric_progress_struct progress;
  46
  47         EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
  48 @@ -346,7 +346,7 @@ errcode_t ext2fs_flush2(ext2_filsys fs, int flags)
  49         group_ptr = (char *) group_shadow;
  50         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) {
  51                 old_desc_blocks = fs->super->s_first_meta_bg;
  52 -               if (old_desc_blocks > fs->super->s_first_meta_bg)
  53 +               if (old_desc_blocks > fs->desc_blocks)
  54                         old_desc_blocks = fs->desc_blocks;
  55         } else
  56                 old_desc_blocks = fs->desc_blocks;
  57 --
  58 2.1.0
  59