From b2472117867fc233fcb634b7370051bcb7fc892c Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Tue, 25 Mar 2014 14:23:52 +0100 Subject: [PATCH 45/49] qcow2: Check maximum L1 size in qcow2_snapshot_load_tmp() (CVE-2014-0143) RH-Author: Kevin Wolf Message-id: <1395753835-7591-46-git-send-email-kwolf@redhat.com> Patchwork-id: n/a O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 45/48] qcow2: Check maximum L1 size in qcow2_snapshot_load_tmp() (CVE-2014-0143) Bugzilla: 1079320 RH-Acked-by: Jeff Cody RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Paolo Bonzini Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079320 Upstream status: Embargoed This avoids an unbounded allocation. Signed-off-by: Kevin Wolf RHEL 7.0 doesn't have commit 7b4c4781, so use error_report() instead of error_setg(). Signed-off-by: Kevin Wolf --- block/qcow2-snapshot.c | 4 ++++ block/qcow2.c | 4 +--- block/qcow2.h | 4 ++++ tests/qemu-iotests/080 | 15 ++++++++++++++- tests/qemu-iotests/080.out | 7 +++++++ 5 files changed, 30 insertions(+), 4 deletions(-) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index b29f7bd..626a8d4 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -635,6 +635,10 @@ int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name) sn = &s->snapshots[snapshot_index]; /* Allocate and read in the snapshot's L1 table */ + if (sn->l1_size > QCOW_MAX_L1_SIZE) { + error_report("Snapshot L1 table too large"); + return -EFBIG; + } new_l1_bytes = sn->l1_size * sizeof(uint64_t); new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512)); diff --git a/block/qcow2.c b/block/qcow2.c index 33b46b8..3f8febc 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -637,9 +637,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, } /* read the level 1 table */ - if (header.l1_size > 0x2000000) { - /* 32 MB L1 table is enough for 2 PB images at 64k cluster size - * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ + if (header.l1_size > QCOW_MAX_L1_SIZE) { error_setg(errp, "Active L1 table too large"); ret = -EFBIG; goto fail; diff --git a/block/qcow2.h b/block/qcow2.h index 9f9f5ae..87e256a 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -44,6 +44,10 @@ * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ #define QCOW_MAX_REFTABLE_SIZE 0x800000 +/* 32 MB L1 table is enough for 2 PB images at 64k cluster size + * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ +#define QCOW_MAX_L1_SIZE 0x2000000 + /* indicate that the refcount of the referenced cluster is exactly one. */ #define QCOW_OFLAG_COPIED (1LL << 63) /* indicate that the cluster is compressed (they never have the copied flag) */ diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080 index 59e7a44..6b3a3e7 100755 --- a/tests/qemu-iotests/080 +++ b/tests/qemu-iotests/080 @@ -30,7 +30,8 @@ status=1 # failure is the default! _cleanup() { - _cleanup_test_img + rm -f $TEST_IMG.snap + _cleanup_test_img } trap "_cleanup; exit \$status" 0 1 2 3 15 @@ -58,6 +59,10 @@ offset_ext_size=$((header_size + 4)) offset_l2_table_0=$((0x40000)) +offset_snap1=$((0x70000)) +offset_snap1_l1_offset=$((offset_snap1 + 0)) +offset_snap1_l1_size=$((offset_snap1 + 8)) + echo echo "== Huge header size ==" _make_test_img 64M @@ -161,6 +166,14 @@ poke_file "$TEST_IMG" "$offset_l2_table_0" "\xbf\xff\xff\xff\xff\xff\x00\x00" poke_file "$TEST_IMG" "$offset_l2_table_0" "\x80\x00\x00\xff\xff\xff\x00\x00" { $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +echo +echo "== Invalid snapshot L1 table ==" +_make_test_img 64M +{ $QEMU_IO -c "write 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_testdir +poke_file "$TEST_IMG" "$offset_snap1_l1_size" "\x10\x00\x00\x00" +{ $QEMU_IMG convert -s test $TEST_IMG $TEST_IMG.snap; } 2>&1 | _filter_testdir + # success, all done echo "*** done" rm -f $seq.full diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out index 4d84fbf..1fa0672 100644 --- a/tests/qemu-iotests/080.out +++ b/tests/qemu-iotests/080.out @@ -74,4 +74,11 @@ wrote 512/512 bytes at offset 0 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) qemu-img: Could not create snapshot 'test': -27 (File too large) qemu-img: Could not create snapshot 'test': -11 (Resource temporarily unavailable) + +== Invalid snapshot L1 table == +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 +wrote 512/512 bytes at offset 0 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +qemu-img: Snapshot L1 table too large +qemu-img: Failed to load snapshot *** done -- 1.7.1