Blame SOURCES/kvm-qcow1-Validate-L2-table-size-CVE-2014-0222.patch

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From 6cec75be66671262a640c0424d93902862f6f1e7 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Mon, 2 Jun 2014 13:54:46 +0200
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Subject: [PATCH 25/30] qcow1: Validate L2 table size (CVE-2014-0222)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1401717288-3918-5-git-send-email-kwolf@redhat.com>
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Patchwork-id: 59099
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O-Subject: [RHEL-7.1/7.0.z qemu-kvm PATCH 4/6] qcow1: Validate L2 table size (CVE-2014-0222)
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Bugzilla: 1097229
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Too large L2 table sizes cause unbounded allocations. Images actually
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created by qemu-img only have 512 byte or 4k L2 tables.
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To keep things consistent with cluster sizes, allow ranges between 512
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bytes and 64k (in fact, down to 1 entry = 8 bytes is technically
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working, but L2 table sizes smaller than a cluster don't make a lot of
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sense).
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This also means that the number of bytes on the virtual disk that are
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described by the same L2 table is limited to at most 8k * 64k or 2^29,
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preventively avoiding any integer overflows.
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Benoit Canet <benoit@irqsave.net>
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(cherry picked from commit 42eb58179b3b215bb507da3262b682b8a2ec10b5)
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---
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 block/qcow.c               |  8 ++++++++
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 tests/qemu-iotests/092     | 15 +++++++++++++++
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 tests/qemu-iotests/092.out | 11 +++++++++++
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 3 files changed, 34 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/qcow.c               |    8 ++++++++
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 tests/qemu-iotests/092     |   15 +++++++++++++++
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 tests/qemu-iotests/092.out |   11 +++++++++++
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 3 files changed, 34 insertions(+), 0 deletions(-)
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diff --git a/block/qcow.c b/block/qcow.c
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index 2efe2fc..f266701 100644
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--- a/block/qcow.c
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+++ b/block/qcow.c
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@@ -137,6 +137,14 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
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         goto fail;
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     }
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+    /* l2_bits specifies number of entries; storing a uint64_t in each entry,
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+     * so bytes = num_entries << 3. */
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+    if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) {
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+        error_setg(errp, "L2 table size must be between 512 and 64k");
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+        ret = -EINVAL;
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+        goto fail;
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+    }
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+
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     if (header.crypt_method > QCOW_CRYPT_AES) {
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         error_setg(errp, "invalid encryption method in qcow header");
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         ret = -EINVAL;
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diff --git a/tests/qemu-iotests/092 b/tests/qemu-iotests/092
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index d060e6f..fb8bacc 100755
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--- a/tests/qemu-iotests/092
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+++ b/tests/qemu-iotests/092
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@@ -44,6 +44,7 @@ _supported_proto generic
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 _supported_os Linux
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 offset_cluster_bits=32
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+offset_l2_bits=33
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 echo
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 echo "== Invalid cluster size =="
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@@ -57,6 +58,20 @@ poke_file "$TEST_IMG" "$offset_cluster_bits" "\x08"
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 poke_file "$TEST_IMG" "$offset_cluster_bits" "\x11"
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 { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+echo
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+echo "== Invalid L2 table size =="
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+_make_test_img 64M
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+poke_file "$TEST_IMG" "$offset_l2_bits" "\xff"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+poke_file "$TEST_IMG" "$offset_l2_bits" "\x05"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+poke_file "$TEST_IMG" "$offset_l2_bits" "\x0e"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+
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+# 1 << 0x1b = 2^31 / L2_CACHE_SIZE
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+poke_file "$TEST_IMG" "$offset_l2_bits" "\x1b"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+
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 # success, all done
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 echo "*** done"
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 rm -f $seq.full
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diff --git a/tests/qemu-iotests/092.out b/tests/qemu-iotests/092.out
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index 8bf8158..73918b3 100644
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--- a/tests/qemu-iotests/092.out
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+++ b/tests/qemu-iotests/092.out
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@@ -10,4 +10,15 @@ qemu-io: can't open device TEST_DIR/t.qcow: Cluster size must be between 512 and
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 no file open, try 'help open'
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 qemu-io: can't open device TEST_DIR/t.qcow: Cluster size must be between 512 and 64k
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 no file open, try 'help open'
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+
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+== Invalid L2 table size ==
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+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
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+qemu-io: can't open device TEST_DIR/t.qcow: L2 table size must be between 512 and 64k
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+no file open, try 'help open'
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+qemu-io: can't open device TEST_DIR/t.qcow: L2 table size must be between 512 and 64k
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+no file open, try 'help open'
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+qemu-io: can't open device TEST_DIR/t.qcow: L2 table size must be between 512 and 64k
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+no file open, try 'help open'
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+qemu-io: can't open device TEST_DIR/t.qcow: L2 table size must be between 512 and 64k
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+no file open, try 'help open'
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 *** done
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-- 
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1.7.1
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