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From 920f41e5268801ff36a4f76ccaf2ac2584ac009e Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Tue, 25 Mar 2014 14:23:19 +0100
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Subject: [PATCH 12/49] bochs: Check catalog_size header field (CVE-2014-0143)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-13-git-send-email-kwolf@redhat.com>
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Patchwork-id: n/a
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O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 12/48] bochs: Check catalog_size header field (CVE-2014-0143)
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Bugzilla: 1079320
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RH-Acked-by: Jeff Cody <jcody@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079320
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Upstream status: Embargoed
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It should neither become negative nor allow unbounded memory
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allocations. This fixes aborts in g_malloc() and an s->catalog_bitmap
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buffer overflow on big endian hosts.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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 block/bochs.c              |   13 +++++++++++++
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 tests/qemu-iotests/078     |   13 +++++++++++++
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 tests/qemu-iotests/078.out |   10 +++++++++-
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 3 files changed, 35 insertions(+), 1 deletions(-)
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diff --git a/block/bochs.c b/block/bochs.c
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index 04cca71..d1b1a2c 100644
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--- a/block/bochs.c
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+++ b/block/bochs.c
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@@ -122,7 +122,14 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
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         bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
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     }
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+    /* Limit to 1M entries to avoid unbounded allocation. This is what is
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+     * needed for the largest image that bximage can create (~8 TB). */
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     s->catalog_size = le32_to_cpu(bochs.catalog);
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+    if (s->catalog_size > 0x100000) {
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+        error_setg(errp, "Catalog size is too large");
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+        return -EFBIG;
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+    }
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+
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     s->catalog_bitmap = g_malloc(s->catalog_size * 4);
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     ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
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@@ -141,6 +148,12 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
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     s->extent_size = le32_to_cpu(bochs.extent);
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+    if (s->catalog_size < bs->total_sectors / s->extent_size) {
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+        error_setg(errp, "Catalog size is too small for this disk size");
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+        ret = -EINVAL;
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+        goto fail;
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+    }
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+
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     qemu_co_mutex_init(&s->lock);
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     return 0;
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diff --git a/tests/qemu-iotests/078 b/tests/qemu-iotests/078
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index 73b573a..902ef0f 100755
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--- a/tests/qemu-iotests/078
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+++ b/tests/qemu-iotests/078
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@@ -43,6 +43,7 @@ _supported_proto generic
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 _supported_os Linux
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 catalog_size_offset=$((0x48))
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+disk_size_offset=$((0x58))
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 echo
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 echo "== Read from a valid image =="
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@@ -55,6 +56,18 @@ _use_sample_img empty.bochs.bz2
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 poke_file "$TEST_IMG" "$catalog_size_offset" "\xff\xff\xff\xff"
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 { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+echo
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+echo "== Overflow for catalog size * sizeof(uint32_t) =="
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+_use_sample_img empty.bochs.bz2
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+poke_file "$TEST_IMG" "$catalog_size_offset" "\x00\x00\x00\x40"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+
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+echo
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+echo "== Too small catalog bitmap for image size =="
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+_use_sample_img empty.bochs.bz2
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+poke_file "$TEST_IMG" "$disk_size_offset" "\x00\xc0\x0f\x00\x00\x00\x00\x7f"
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+{ $QEMU_IO -c "read 2T 4k" $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/078.out b/tests/qemu-iotests/078.out
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index ef8c42d..7254693 100644
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--- a/tests/qemu-iotests/078.out
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+++ b/tests/qemu-iotests/078.out
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@@ -5,6 +5,14 @@ read 512/512 bytes at offset 0
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 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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 == Negative catalog size ==
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-qemu-io: can't open device TEST_DIR/empty.bochs: Could not open 'TEST_DIR/empty.bochs': Interrupted system call
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+qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too large
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+no file open, try 'help open'
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+
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+== Overflow for catalog size * sizeof(uint32_t) ==
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+qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too large
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+no file open, try 'help open'
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+
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+== Too small catalog bitmap for image size ==
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+qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size
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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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