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From:

Kevin Wolf

Subject:

[Qemu-devel] [PATCH 4/5] qcow1: Validate image size (CVE-2014-0223)

Date:

Mon, 12 May 2014 15:04:10 +0200

A huge image size could cause s->l1_size to overflow. Make sure that images never require a L1 table larger than what fits in s->l1_size.

This cannot only cause unbounded allocations, but also the allocation of a too small L1 table, resulting in out-of-bounds array accesses (both reads and writes).

Signed-off-by: Kevin Wolf address@hidden

block/qcow.c | 16 +++++++++++++±- tests/qemu-iotests/092 | 9 +++++++++ tests/qemu-iotests/092.out | 7 +++++++ 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/block/qcow.c b/block/qcow.c index e8038e5…3566c05 100644 — a/block/qcow.c +++ b/block/qcow.c @@ -61,7 +61,7 @@ typedef struct BDRVQcowState { int cluster_sectors; int l2_bits; int l2_size;

• int l1_size;

• unsigned int l1_size; uint64_t cluster_offset_mask; uint64_t l1_table_offset; uint64_t *l1_table; @@ -166,7 +166,19 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,

  /* read the level 1 table */ shift = s->cluster_bits + s->l2_bits;

• s->l1_size = (header.size + (1LL << shift) - 1) >> shift;

• if (header.size > UINT64_MAX - (1LL << shift)) {

•    error\_setg(errp, "Image too large");
  

•    ret = -EINVAL;
  

•    goto fail;
  

• } else {

•    uint64\_t l1\_size = (header.size + (1LL << shift) - 1) >> shift;
  

•    if (l1\_size > INT\_MAX / sizeof(uint64\_t)) {
  

•        error\_setg(errp, "Image too large");
  

•        ret = -EINVAL;
  

•        goto fail;
  

•    }
  

•    s->l1\_size = l1\_size;
  

• }

  s->l1_table_offset = header.l1_table_offset; s->l1_table = g_malloc(s->l1_size * sizeof(uint64_t)); diff --git a/tests/qemu-iotests/092 b/tests/qemu-iotests/092 index 2196cce…26a1324 100755 — a/tests/qemu-iotests/092 +++ b/tests/qemu-iotests/092 @@ -43,6 +43,7 @@ _supported_fmt qcow _supported_proto generic _supported_os Linux

+offset_size=24 offset_cluster_bits=32 offset_l2_bits=33

@@ -64,6 +65,14 @@ poke_file “$TEST_IMG” “$offset_l2_bits” “\xff” poke_file “$TEST_IMG” “$offset_l2_bits” “\x1b” { $QEMU_IO -c “read 0 512” $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir

+echo +echo “== Invalid size ==” +_make_test_img 64M +poke_file “$TEST_IMG” “$offset_size” “\xee\xee\xee\xee\xee\xee\xee\xee” +{ $QEMU_IO -c “read 0 512” $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +poke_file “$TEST_IMG” “$offset_size” “\x7f\xff\xff\xff\xff\xff\xff\xff” +{ $QEMU_IO -c “write 0 64M” $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir

success, all done

echo “*** done” rm -f $seq.full diff --git a/tests/qemu-iotests/092.out b/tests/qemu-iotests/092.out index 45a7ac8…c3678a0 100644 — a/tests/qemu-iotests/092.out +++ b/tests/qemu-iotests/092.out @@ -13,4 +13,11 @@ qemu-io: can’t open device TEST_DIR/t.qcow: L2 table size must be between 512 an no file open, try ‘help open’ qemu-io: can’t open device TEST_DIR/t.qcow: L2 table size must be between 512 and 64k no file open, try ‘help open’

+== Invalid size == +Formatting 'TEST_DIR/t.IMGFMT’, fmt=IMGFMT size=67108864 +qemu-io: can’t open device TEST_DIR/t.qcow: Image too large +no file open, try ‘help open’ +qemu-io: can’t open device TEST_DIR/t.qcow: Image too large +no file open, try ‘help open’ *** done – 1.8.3.1

• [Qemu-devel] [PATCH 0/5] qcow1: Input validation fixes, Kevin Wolf, 2014/05/12

  • [Qemu-devel] [PATCH 2/5] qcow1: Check maximum cluster size, Kevin Wolf, 2014/05/12
    • Re: [Qemu-devel] [PATCH 2/5] qcow1: Check maximum cluster size, Benoît Canet, 2014/05/12
  • [Qemu-devel] [PATCH 1/5] qcow1: Make padding in the header explicit, Kevin Wolf, 2014/05/12
    • Re: [Qemu-devel] [PATCH 1/5] qcow1: Make padding in the header explicit, Benoît Canet, 2014/05/12
  • [Qemu-devel] [PATCH 3/5] qcow1: Validate L2 table size (CVE-2014-0222), Kevin Wolf, 2014/05/12
    • Re: [Qemu-devel] [PATCH 3/5] qcow1: Validate L2 table size (CVE-2014-0222), Benoît Canet, 2014/05/12
  • [Qemu-devel] [PATCH 4/5] qcow1: Validate image size (CVE-2014-0223), Kevin Wolf <=
    • Re: [Qemu-devel] [PATCH 4/5] qcow1: Validate image size (CVE-2014-0223), Benoît Canet, 2014/05/12
      • Re: [Qemu-devel] [PATCH 4/5] qcow1: Validate image size (CVE-2014-0223), Kevin Wolf, 2014/05/12
      • Re: [Qemu-devel] [PATCH 4/5] qcow1: Validate image size (CVE-2014-0223), Benoît Canet, 2014/05/12
      • Re: [Qemu-devel] [PATCH 4/5] qcow1: Validate image size (CVE-2014-0223), Benoît Canet, 2014/05/12
      • Re: [Qemu-devel] [PATCH 4/5] qcow1: Validate image size (CVE-2014-0223), Kevin Wolf, 2014/05/13
  • [Qemu-devel] [PATCH 5/5] qcow1: Stricter backing file length check, Kevin Wolf, 2014/05/12
    • Re: [Qemu-devel] [PATCH 5/5] qcow1: Stricter backing file length check*, Benoît Canet, 2014/05/12
  • Re: [Qemu-devel] [PATCH 0/5] qcow1: Input validation fixes, Stefan Hajnoczi, 2014/05/13

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