From 6a83f8b5bec6f59e56cc49bd49e4c3f8f805d56f Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 26 Mar 2014 13:06:06 +0100 Subject: qcow2: Check maximum L1 size in qcow2_snapshot_load_tmp() (CVE-2014-0143) This avoids an unbounded allocation. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Signed-off-by: Stefan Hajnoczi --- block/qcow2-snapshot.c | 4 ++++ block/qcow2.c | 4 +--- block/qcow2.h | 4 ++++ tests/qemu-iotests/080 | 15 ++++++++++++++- tests/qemu-iotests/080.out | 6 ++++++ 5 files changed, 29 insertions(+), 4 deletions(-) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 715168e..5db4f30 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -680,6 +680,10 @@ int qcow2_snapshot_load_tmp(BlockDriverState *bs, sn = &s->snapshots[snapshot_index]; /* Allocate and read in the snapshot's L1 table */ + if (sn->l1_size > QCOW_MAX_L1_SIZE) { + error_setg(errp, "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 be48a27..bb6000f 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -638,9 +638,7 @@ 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 3649465..f28e7d9 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 (1ULL << 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..f7a943c 100644 --- a/tests/qemu-iotests/080.out +++ b/tests/qemu-iotests/080.out @@ -74,4 +74,10 @@ 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: Failed to load snapshot: Snapshot L1 table too large *** done -- cgit v1.1