From 54e639827c618c74ecb47690754f0299c2e35750 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 25 Mar 2014 14:23:13 +0100 Subject: [PATCH 06/49] block/cloop: refuse images with huge offsets arrays (CVE-2014-0144) RH-Author: Kevin Wolf Message-id: <1395753835-7591-7-git-send-email-kwolf@redhat.com> Patchwork-id: n/a O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 06/48] block/cloop: refuse images with huge offsets arrays (CVE-2014-0144) Bugzilla: 1079455 RH-Acked-by: Jeff Cody RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Paolo Bonzini From: Stefan Hajnoczi Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079455 Upstream status: Embargoed Limit offsets_size to 512 MB so that: 1. g_malloc() does not abort due to an unreasonable size argument. 2. offsets_size does not overflow the bdrv_pread() int size argument. This limit imposes a maximum image size of 16 TB at 256 KB block size. Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/cloop.c | 9 +++++++++ tests/qemu-iotests/075 | 6 ++++++ tests/qemu-iotests/075.out | 4 ++++ 3 files changed, 19 insertions(+), 0 deletions(-) diff --git a/block/cloop.c b/block/cloop.c index 563e916..844665e 100644 --- a/block/cloop.c +++ b/block/cloop.c @@ -107,6 +107,15 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags, return -EINVAL; } offsets_size = s->n_blocks * sizeof(uint64_t); + if (offsets_size > 512 * 1024 * 1024) { + /* Prevent ridiculous offsets_size which causes memory allocation to + * fail or overflows bdrv_pread() size. In practice the 512 MB + * offsets[] limit supports 16 TB images at 256 KB block size. + */ + error_setg(errp, "image requires too many offsets, " + "try increasing block size"); + return -EINVAL; + } s->offsets = g_malloc(offsets_size); ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size); diff --git a/tests/qemu-iotests/075 b/tests/qemu-iotests/075 index 9ce6b1f..9c00fa8 100755 --- a/tests/qemu-iotests/075 +++ b/tests/qemu-iotests/075 @@ -74,6 +74,12 @@ _use_sample_img simple-pattern.cloop.bz2 poke_file "$TEST_IMG" "$n_blocks_offset" "\xff\xff\xff\xff" $QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir +echo +echo "== refuse images that require too many offsets ===" +_use_sample_img simple-pattern.cloop.bz2 +poke_file "$TEST_IMG" "$n_blocks_offset" "\x04\x00\x00\x01" +$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir + # success, all done echo "*** done" rm -f $seq.full diff --git a/tests/qemu-iotests/075.out b/tests/qemu-iotests/075.out index a771789..7cdaee1 100644 --- a/tests/qemu-iotests/075.out +++ b/tests/qemu-iotests/075.out @@ -19,4 +19,8 @@ no file open, try 'help open' == offsets_size overflow === qemu-io: can't open device TEST_DIR/simple-pattern.cloop: n_blocks 4294967295 must be 536870911 or less no file open, try 'help open' + +== refuse images that require too many offsets === +qemu-io: can't open device TEST_DIR/simple-pattern.cloop: image requires too many offsets, try increasing block size +no file open, try 'help open' *** done -- 1.7.1