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From ba8c0cc73f3a13b5621c8fe44eb8af20ddb9c5d0 Mon Sep 17 00:00:00 2001
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Tue, 25 Mar 2014 14:23:11 +0100
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Subject: [PATCH 04/49] block/cloop: validate block_size header field (CVE-2014-0144)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-5-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 04/48] block/cloop: validate block_size header field (CVE-2014-0144)
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Bugzilla: 1079455
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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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From: Stefan Hajnoczi <stefanha@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079455
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Upstream status: Embargoed
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Avoid unbounded s->uncompressed_block memory allocation by checking that
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the block_size header field has a reasonable value. Also enforce the
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assumption that the value is a non-zero multiple of 512.
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These constraints conform to cloop 2.639's code so we accept existing
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image files.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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 block/cloop.c              |   23 +++++++++++++++++++++++
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 tests/qemu-iotests/075     |   20 ++++++++++++++++++++
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 tests/qemu-iotests/075.out |   12 ++++++++++++
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 3 files changed, 55 insertions(+), 0 deletions(-)
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diff --git a/block/cloop.c b/block/cloop.c
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index b907023..f021663 100644
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--- a/block/cloop.c
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+++ b/block/cloop.c
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@@ -26,6 +26,9 @@
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 #include "qemu/module.h"
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 #include <zlib.h>
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+/* Maximum compressed block size */
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+#define MAX_BLOCK_SIZE (64 * 1024 * 1024)
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+
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 typedef struct BDRVCloopState {
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     CoMutex lock;
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     uint32_t block_size;
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@@ -68,6 +71,26 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
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         return ret;
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     }
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     s->block_size = be32_to_cpu(s->block_size);
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+    if (s->block_size % 512) {
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+        error_setg(errp, "block_size %u must be a multiple of 512",
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+                   s->block_size);
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+        return -EINVAL;
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+    }
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+    if (s->block_size == 0) {
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+        error_setg(errp, "block_size cannot be zero");
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+        return -EINVAL;
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+    }
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+
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+    /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
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+     * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
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+     * need a buffer this big.
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+     */
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+    if (s->block_size > MAX_BLOCK_SIZE) {
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+        error_setg(errp, "block_size %u must be %u MB or less",
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+                   s->block_size,
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+                   MAX_BLOCK_SIZE / (1024 * 1024));
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+        return -EINVAL;
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+    }
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     ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
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     if (ret < 0) {
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diff --git a/tests/qemu-iotests/075 b/tests/qemu-iotests/075
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index 88ae8bb..8f54a99 100755
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--- a/tests/qemu-iotests/075
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+++ b/tests/qemu-iotests/075
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@@ -42,11 +42,31 @@ _supported_fmt cloop
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 _supported_proto generic
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 _supported_os Linux
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+block_size_offset=128
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+
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 echo
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 echo "== check that the first sector can be read =="
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 _use_sample_img simple-pattern.cloop.bz2
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 $QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
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+echo
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+echo "== block_size must be a multiple of 512 =="
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+_use_sample_img simple-pattern.cloop.bz2
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+poke_file "$TEST_IMG" "$block_size_offset" "\x00\x00\x02\x01"
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+$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
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+
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+echo
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+echo "== block_size cannot be zero =="
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+_use_sample_img simple-pattern.cloop.bz2
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+poke_file "$TEST_IMG" "$block_size_offset" "\x00\x00\x00\x00"
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+$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
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+
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+echo
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+echo "== huge block_size ==="
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+_use_sample_img simple-pattern.cloop.bz2
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+poke_file "$TEST_IMG" "$block_size_offset" "\xff\xff\xfe\x00"
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+$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/075.out b/tests/qemu-iotests/075.out
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index 26661fa..d362c95 100644
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--- a/tests/qemu-iotests/075.out
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+++ b/tests/qemu-iotests/075.out
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@@ -3,4 +3,16 @@ QA output created by 075
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 == check that the first sector can be read ==
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 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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+
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+== block_size must be a multiple of 512 ==
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+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 513 must be a multiple of 512
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+no file open, try 'help open'
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+
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+== block_size cannot be zero ==
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+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size cannot be zero
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+no file open, try 'help open'
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+
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+== huge block_size ===
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+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 4294966784 must be 64 MB or less
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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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