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From 71ae37ec9806ab76afcdb40cf5f080af378848ac Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Thu, 15 May 2014 16:10:11 +0200
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Subject: [PATCH] qcow1: Validate L2 table size (CVE-2014-0222)
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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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Conflicts:
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tests/qemu-iotests/092
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tests/qemu-iotests/092.out
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---
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block/qcow.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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diff --git a/block/qcow.c b/block/qcow.c
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index 26bb923..8718ca5 100644
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--- a/block/qcow.c
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+++ b/block/qcow.c
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@@ -138,6 +138,14 @@ 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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