39 lines
1.6 KiB
Diff
39 lines
1.6 KiB
Diff
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References: bsc#877642
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Subject: qcow1: Validate L2 table size (CVE-2014-0222)
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From: Kevin Wolf kwolf@redhat.com Thu May 15 16:10:11 2014 +0200
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Date: Mon May 19 11:36:49 2014 +0200:
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Git: 42eb58179b3b215bb507da3262b682b8a2ec10b5
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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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Index: xen-4.5.1-testing/tools/qemu-xen-traditional-dir-remote/block-qcow.c
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===================================================================
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--- xen-4.5.1-testing.orig/tools/qemu-xen-traditional-dir-remote/block-qcow.c
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+++ xen-4.5.1-testing/tools/qemu-xen-traditional-dir-remote/block-qcow.c
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@@ -126,6 +126,10 @@ static int qcow_open(BlockDriverState *b
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goto fail;
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if (header.size <= 1 || header.cluster_bits < 9)
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goto fail;
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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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+ goto fail;
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if (header.crypt_method > QCOW_CRYPT_AES)
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goto fail;
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s->crypt_method_header = header.crypt_method;
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