From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43697) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WjsUI-0004dM-RO for qemu-devel@nongnu.org; Mon, 12 May 2014 11:50:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WjsUC-0005KM-Lx for qemu-devel@nongnu.org; Mon, 12 May 2014 11:49:58 -0400 Received: from lputeaux-656-01-25-125.w80-12.abo.wanadoo.fr ([80.12.84.125]:47908 helo=paradis.irqsave.net) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WjsUC-0005K3-CW for qemu-devel@nongnu.org; Mon, 12 May 2014 11:49:52 -0400 Date: Mon, 12 May 2014 17:50:24 +0200 From: =?iso-8859-1?Q?Beno=EEt?= Canet Message-ID: <20140512155024.GG7858@irqsave.net> References: <1399899851-5641-1-git-send-email-kwolf@redhat.com> <1399899851-5641-5-git-send-email-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1399899851-5641-5-git-send-email-kwolf@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 4/5] qcow1: Validate image size (CVE-2014-0223) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, stefanha@redhat.com, ppandit@redhat.com The Monday 12 May 2014 =E0 15:04:10 (+0200), Kevin Wolf wrote : > 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. >=20 > This cannot only cause unbounded allocations, but also the allocation o= f > a too small L1 table, resulting in out-of-bounds array accesses (both > reads and writes). >=20 > Signed-off-by: Kevin Wolf > --- > block/qcow.c | 16 ++++++++++++++-- > tests/qemu-iotests/092 | 9 +++++++++ > tests/qemu-iotests/092.out | 7 +++++++ > 3 files changed, 30 insertions(+), 2 deletions(-) >=20 > 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, > =20 > /* read the level 1 table */ > shift =3D s->cluster_bits + s->l2_bits; > - s->l1_size =3D (header.size + (1LL << shift) - 1) >> shift; > + if (header.size > UINT64_MAX - (1LL << shift)) { I won't be much helpfull but this feel wrong. Does each l1 entry point to an l2 chunk mapping itself to 1 << (s->cluste= r_bits + s->l2_bits) bytes ? Where the size for the L2 chunk themselves is accounted ? > + error_setg(errp, "Image too large"); > + ret =3D -EINVAL; > + goto fail; > + } else { > + uint64_t l1_size =3D (header.size + (1LL << shift) - 1) >> shi= ft; > + if (l1_size > INT_MAX / sizeof(uint64_t)) { > + error_setg(errp, "Image too large"); > + ret =3D -EINVAL; > + goto fail; > + } > + s->l1_size =3D l1_size; > + } > =20 > s->l1_table_offset =3D header.l1_table_offset; > s->l1_table =3D 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 > =20 > +offset_size=3D24 > offset_cluster_bits=3D32 > offset_l2_bits=3D33 > =20 > @@ -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" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filt= er_testdir > =20 > +echo > +echo "=3D=3D Invalid size =3D=3D" > +_make_test_img 64M > +poke_file "$TEST_IMG" "$offset_size" "\xee\xee\xee\xee\xee\xee\xee\xee= " > +{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filt= er_testdir > +poke_file "$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 | _fil= ter_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 betw= een 512 and 64k > no file open, try 'help open' > + > +=3D=3D Invalid size =3D=3D > +Formatting 'TEST_DIR/t.IMGFMT', fmt=3DIMGFMT size=3D67108864=20 > +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 > --=20 > 1.8.3.1 >=20 >=20