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qcow2: Check maximum L1 size in qcow2_snapshot_load_tmp() (CVE-2014-0143) 

This avoids an unbounded allocation.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2014-03-26 13:06:06 +01:00 committed by Stefan Hajnoczi
parent c05e4667be
commit 6a83f8b5be
5 changed files with 29 additions and 4 deletions
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4
block/qcow2-snapshot.c
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@ -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));

4
block/qcow2.c
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@ -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;

4
block/qcow2.h
View File

@ -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) */

15
tests/qemu-iotests/080
View File

@ -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

6
tests/qemu-iotests/080.out
View File

@ -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