t/t5313-pack-bounds-checks.sh

   1 #!/bin/sh
   2
   3 test_description='bounds-checking of access to mmapped on-disk file formats'
   4 . ./test-lib.sh
   5
   6 clear_base () {
   7         test_when_finished 'restore_base' &&
   8         rm -f $base
   9 }
  10
  11 restore_base () {
  12         cp base-backup/* .git/objects/pack/
  13 }
  14
  15 do_pack () {
  16         pack_objects=$1; shift
  17         sha1=$(
  18                 for i in $pack_objects
  19                 do
  20                         echo $i
  21                 done | git pack-objects "$@" .git/objects/pack/pack
  22         ) &&
  23         pack=.git/objects/pack/pack-$sha1.pack &&
  24         idx=.git/objects/pack/pack-$sha1.idx &&
  25         chmod +w $pack $idx &&
  26         test_when_finished 'rm -f "$pack" "$idx"'
  27 }
  28
  29 munge () {
  30         printf "$3" | dd of="$1" bs=1 conv=notrunc seek=$2
  31 }
  32
  33 # Offset in a v2 .idx to its initial and extended offset tables. For an index
  34 # with "nr" objects, this is:
  35 #
  36 #   magic(4) + version(4) + fan-out(4*256) + sha1s(20*nr) + crc(4*nr),
  37 #
  38 # for the initial, and another ofs(4*nr) past that for the extended.
  39 #
  40 ofs_table () {
  41         echo $((4 + 4 + 4*256 + $(test_oid rawsz)*$1 + 4*$1))
  42 }
  43 extended_table () {
  44         echo $(($(ofs_table "$1") + 4*$1))
  45 }
  46
  47 test_expect_success 'setup' '
  48         test_oid_cache <<-EOF
  49         oid000 sha1:1485
  50         oid000 sha256:4222
  51
  52         oidfff sha1:74
  53         oidfff sha256:1350
  54         EOF
  55 '
  56
  57 test_expect_success 'set up base packfile and variables' '
  58         # the hash of this content starts with ff, which
  59         # makes some later computations much simpler
  60         echo $(test_oid oidfff) >file &&
  61         git add file &&
  62         git commit -m base &&
  63         git repack -ad &&
  64         base=$(echo .git/objects/pack/*) &&
  65         chmod +w $base &&
  66         mkdir base-backup &&
  67         cp $base base-backup/ &&
  68         object=$(git rev-parse HEAD:file)
  69 '
  70
  71 test_expect_success 'pack/index object count mismatch' '
  72         do_pack $object &&
  73         munge $pack 8 "\377\0\0\0" &&
  74         clear_base &&
  75
  76         # We enumerate the objects from the completely-fine
  77         # .idx, but notice later that the .pack is bogus
  78         # and fail to show any data.
  79         echo "$object missing" >expect &&
  80         git cat-file --batch-all-objects --batch-check >actual &&
  81         test_cmp expect actual &&
  82
  83         # ...and here fail to load the object (without segfaulting),
  84         # but fallback to a good copy if available.
  85         test_must_fail git cat-file blob $object &&
  86         restore_base &&
  87         git cat-file blob $object >actual &&
  88         test_cmp file actual &&
  89
  90         # ...and make sure that index-pack --verify, which has its
  91         # own reading routines, does not segfault.
  92         test_must_fail git index-pack --verify $pack
  93 '
  94
  95 test_expect_success 'matched bogus object count' '
  96         do_pack $object &&
  97         munge $pack 8 "\377\0\0\0" &&
  98         munge $idx $((255 * 4)) "\377\0\0\0" &&
  99         clear_base &&
 100
 101         # Unlike above, we should notice early that the .idx is totally
 102         # bogus, and not even enumerate its contents.
 103         git cat-file --batch-all-objects --batch-check >actual &&
 104         test_must_be_empty actual &&
 105
 106         # But as before, we can do the same object-access checks.
 107         test_must_fail git cat-file blob $object &&
 108         restore_base &&
 109         git cat-file blob $object >actual &&
 110         test_cmp file actual &&
 111
 112         test_must_fail git index-pack --verify $pack
 113 '
 114
 115 # Note that we cannot check the fallback case for these
 116 # further .idx tests, as we notice the problem in functions
 117 # whose interface doesn't allow an error return (like use_pack()),
 118 # and thus we just die().
 119 #
 120 # There's also no point in doing enumeration tests, as
 121 # we are munging offsets here, which are about looking up
 122 # specific objects.
 123
 124 test_expect_success 'bogus object offset (v1)' '
 125         do_pack $object --index-version=1 &&
 126         munge $idx $((4 * 256)) "\377\0\0\0" &&
 127         clear_base &&
 128         test_must_fail git cat-file blob $object &&
 129         test_must_fail git index-pack --verify $pack
 130 '
 131
 132 test_expect_success 'bogus object offset (v2, no msb)' '
 133         do_pack $object --index-version=2 &&
 134         munge $idx $(ofs_table 1) "\0\377\0\0" &&
 135         clear_base &&
 136         test_must_fail git cat-file blob $object &&
 137         test_must_fail git index-pack --verify $pack
 138 '
 139
 140 test_expect_success 'bogus offset into v2 extended table' '
 141         do_pack $object --index-version=2 &&
 142         munge $idx $(ofs_table 1) "\377\0\0\0" &&
 143         clear_base &&
 144         test_must_fail git cat-file blob $object &&
 145         test_must_fail git index-pack --verify $pack
 146 '
 147
 148 test_expect_success 'bogus offset inside v2 extended table' '
 149         # We need two objects here, so we can plausibly require
 150         # an extended table (if the first object were larger than 2^31).
 151         #
 152         # Note that the value is important here. We want $object as
 153         # the second entry in sorted-hash order. The hash of this object starts
 154         # with "000", which sorts before that of $object (which starts
 155         # with "fff").
 156         second=$(test_oid oid000 | git hash-object -w --stdin) &&
 157         do_pack "$object $second" --index-version=2 &&
 158
 159         # We have to make extra room for the table, so we cannot
 160         # just munge in place as usual.
 161         {
 162                 dd if=$idx bs=1 count=$(($(ofs_table 2) + 4)) &&
 163                 printf "\200\0\0\0" &&
 164                 printf "\377\0\0\0\0\0\0\0" &&
 165                 dd if=$idx bs=1 skip=$(extended_table 2)
 166         } >tmp &&
 167         mv tmp "$idx" &&
 168         clear_base &&
 169         test_must_fail git cat-file blob $object &&
 170         test_must_fail git index-pack --verify $pack
 171 '
 172
 173 test_expect_success 'bogus OFS_DELTA in packfile' '
 174         # Generate a pack with a delta in it.
 175         base=$(test-tool genrandom foo 3000 | git hash-object --stdin -w) &&
 176         delta=$(test-tool genrandom foo 2000 | git hash-object --stdin -w) &&
 177         do_pack "$base $delta" --delta-base-offset &&
 178         rm -f .git/objects/??/* &&
 179
 180         # Double check that we have the delta we expect.
 181         echo $base >expect &&
 182         echo $delta | git cat-file --batch-check="%(deltabase)" >actual &&
 183         test_cmp expect actual &&
 184
 185         # Now corrupt it. We assume the varint size for the delta is small
 186         # enough to fit in the first byte (which it should be, since it
 187         # is a pure deletion from the base), and that original ofs_delta
 188         # takes 2 bytes (which it should, as it should be ~3000).
 189         ofs=$(git show-index <$idx | grep $delta | cut -d" " -f1) &&
 190         munge $pack $(($ofs + 1)) "\177\377" &&
 191         test_must_fail git cat-file blob $delta >/dev/null
 192 '
 193
 194 test_done