From ba8c0cc73f3a13b5621c8fe44eb8af20ddb9c5d0 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 25 Mar 2014 14:23:11 +0100 Subject: [PATCH 04/49] block/cloop: validate block_size header field (CVE-2014-0144) RH-Author: Kevin Wolf Message-id: <1395753835-7591-5-git-send-email-kwolf@redhat.com> Patchwork-id: n/a O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 04/48] block/cloop: validate block_size header field (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 Avoid unbounded s->uncompressed_block memory allocation by checking that the block_size header field has a reasonable value. Also enforce the assumption that the value is a non-zero multiple of 512. These constraints conform to cloop 2.639's code so we accept existing image files. Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/cloop.c | 23 +++++++++++++++++++++++ tests/qemu-iotests/075 | 20 ++++++++++++++++++++ tests/qemu-iotests/075.out | 12 ++++++++++++ 3 files changed, 55 insertions(+), 0 deletions(-) diff --git a/block/cloop.c b/block/cloop.c index b907023..f021663 100644 --- a/block/cloop.c +++ b/block/cloop.c @@ -26,6 +26,9 @@ #include "qemu/module.h" #include +/* Maximum compressed block size */ +#define MAX_BLOCK_SIZE (64 * 1024 * 1024) + typedef struct BDRVCloopState { CoMutex lock; uint32_t block_size; @@ -68,6 +71,26 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags, return ret; } s->block_size = be32_to_cpu(s->block_size); + if (s->block_size % 512) { + error_setg(errp, "block_size %u must be a multiple of 512", + s->block_size); + return -EINVAL; + } + if (s->block_size == 0) { + error_setg(errp, "block_size cannot be zero"); + return -EINVAL; + } + + /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but + * we can accept more. Prevent ridiculous values like 4 GB - 1 since we + * need a buffer this big. + */ + if (s->block_size > MAX_BLOCK_SIZE) { + error_setg(errp, "block_size %u must be %u MB or less", + s->block_size, + MAX_BLOCK_SIZE / (1024 * 1024)); + return -EINVAL; + } ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4); if (ret < 0) { diff --git a/tests/qemu-iotests/075 b/tests/qemu-iotests/075 index 88ae8bb..8f54a99 100755 --- a/tests/qemu-iotests/075 +++ b/tests/qemu-iotests/075 @@ -42,11 +42,31 @@ _supported_fmt cloop _supported_proto generic _supported_os Linux +block_size_offset=128 + echo echo "== check that the first sector can be read ==" _use_sample_img simple-pattern.cloop.bz2 $QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir +echo +echo "== block_size must be a multiple of 512 ==" +_use_sample_img simple-pattern.cloop.bz2 +poke_file "$TEST_IMG" "$block_size_offset" "\x00\x00\x02\x01" +$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir + +echo +echo "== block_size cannot be zero ==" +_use_sample_img simple-pattern.cloop.bz2 +poke_file "$TEST_IMG" "$block_size_offset" "\x00\x00\x00\x00" +$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir + +echo +echo "== huge block_size ===" +_use_sample_img simple-pattern.cloop.bz2 +poke_file "$TEST_IMG" "$block_size_offset" "\xff\xff\xfe\x00" +$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 26661fa..d362c95 100644 --- a/tests/qemu-iotests/075.out +++ b/tests/qemu-iotests/075.out @@ -3,4 +3,16 @@ QA output created by 075 == check that the first sector can be read == read 512/512 bytes at offset 0 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) + +== block_size must be a multiple of 512 == +qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 513 must be a multiple of 512 +no file open, try 'help open' + +== block_size cannot be zero == +qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size cannot be zero +no file open, try 'help open' + +== huge block_size === +qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 4294966784 must be 64 MB or less +no file open, try 'help open' *** done -- 1.7.1