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Blame SOURCES/kvm-qcow2-Validate-snapshot-table-offset-size-CVE-2014-0.patch

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From 2318681bf850996a3e9c682ca3290aa9f05fd15c 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 14:23:31 +0100
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Subject: [PATCH 24/49] qcow2: Validate snapshot table offset/size (CVE-2014-0144)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-25-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 24/48] qcow2: Validate snapshot table offset/size (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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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079455
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Upstream status: Embargoed
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This avoid unbounded memory allocation and fixes a potential buffer
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overflow on 32 bit hosts.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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 block/qcow2-snapshot.c     |   29 ++++-------------------------
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 block/qcow2.c              |   15 +++++++++++++++
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 block/qcow2.h              |   29 ++++++++++++++++++++++++++++-
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 tests/qemu-iotests/080     |   27 +++++++++++++++++++++++++++
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 tests/qemu-iotests/080.out |   17 +++++++++++++++++
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 5 files changed, 91 insertions(+), 26 deletions(-)
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diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
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index aa88c51..5d73506 100644
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--- a/block/qcow2-snapshot.c
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+++ b/block/qcow2-snapshot.c
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@@ -26,31 +26,6 @@
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 #include "block/block_int.h"
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 #include "block/qcow2.h"
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-typedef struct QEMU_PACKED QCowSnapshotHeader {
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-    /* header is 8 byte aligned */
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-    uint64_t l1_table_offset;
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-
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-    uint32_t l1_size;
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-    uint16_t id_str_size;
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-    uint16_t name_size;
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-
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-    uint32_t date_sec;
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-    uint32_t date_nsec;
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-
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-    uint64_t vm_clock_nsec;
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-
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-    uint32_t vm_state_size;
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-    uint32_t extra_data_size; /* for extension */
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-    /* extra data follows */
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-    /* id_str follows */
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-    /* name follows  */
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-} QCowSnapshotHeader;
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-
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-typedef struct QEMU_PACKED QCowSnapshotExtraData {
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-    uint64_t vm_state_size_large;
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-    uint64_t disk_size;
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-} QCowSnapshotExtraData;
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-
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 void qcow2_free_snapshots(BlockDriverState *bs)
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 {
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     BDRVQcowState *s = bs->opaque;
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@@ -334,6 +309,10 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
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     uint64_t *l1_table = NULL;
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     int64_t l1_table_offset;
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+    if (s->nb_snapshots >= QCOW_MAX_SNAPSHOTS) {
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+        return -EFBIG;
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+    }
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+
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     memset(sn, 0, sizeof(*sn));
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     /* Generate an ID if it wasn't passed */
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diff --git a/block/qcow2.c b/block/qcow2.c
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index 5513fac..8c74dea 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -622,6 +622,21 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
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         goto fail;
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     }
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+    /* Snapshot table offset/length */
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+    if (header.nb_snapshots > QCOW_MAX_SNAPSHOTS) {
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+        error_setg(errp, "Too many snapshots");
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+        ret = -EINVAL;
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+        goto fail;
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+    }
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+
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+    ret = validate_table_offset(bs, header.snapshots_offset,
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+                                header.nb_snapshots,
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+                                sizeof(QCowSnapshotHeader));
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+    if (ret < 0) {
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+        error_setg(errp, "Invalid snapshot table offset");
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+        goto fail;
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+    }
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+
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     s->snapshots_offset = header.snapshots_offset;
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     s->nb_snapshots = header.nb_snapshots;
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diff --git a/block/qcow2.h b/block/qcow2.h
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index 4a653c5..5efc96e 100644
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--- a/block/qcow2.h
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+++ b/block/qcow2.h
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@@ -38,6 +38,7 @@
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 #define QCOW_CRYPT_AES  1
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 #define QCOW_MAX_CRYPT_CLUSTERS 32
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+#define QCOW_MAX_SNAPSHOTS 65536
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 /* indicate that the refcount of the referenced cluster is exactly one. */
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 #define QCOW_OFLAG_COPIED     (1LL << 63)
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@@ -97,6 +98,32 @@ typedef struct QCowHeader {
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     uint32_t header_length;
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 } QCowHeader;
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+typedef struct QEMU_PACKED QCowSnapshotHeader {
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+    /* header is 8 byte aligned */
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+    uint64_t l1_table_offset;
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+
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+    uint32_t l1_size;
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+    uint16_t id_str_size;
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+    uint16_t name_size;
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+
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+    uint32_t date_sec;
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+    uint32_t date_nsec;
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+
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+    uint64_t vm_clock_nsec;
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+
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+    uint32_t vm_state_size;
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+    uint32_t extra_data_size; /* for extension */
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+    /* extra data follows */
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+    /* id_str follows */
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+    /* name follows  */
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+} QCowSnapshotHeader;
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+
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+typedef struct QEMU_PACKED QCowSnapshotExtraData {
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+    uint64_t vm_state_size_large;
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+    uint64_t disk_size;
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+} QCowSnapshotExtraData;
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+
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+
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 typedef struct QCowSnapshot {
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     uint64_t l1_table_offset;
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     uint32_t l1_size;
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@@ -202,7 +229,7 @@ typedef struct BDRVQcowState {
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     AES_KEY aes_decrypt_key;
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     uint64_t snapshots_offset;
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     int snapshots_size;
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-    int nb_snapshots;
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+    unsigned int nb_snapshots;
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     QCowSnapshot *snapshots;
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     int flags;
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diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080
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index f58ac73..8a8b460 100755
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--- a/tests/qemu-iotests/080
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+++ b/tests/qemu-iotests/080
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@@ -47,6 +47,8 @@ header_size=104
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 offset_backing_file_offset=8
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 offset_refcount_table_offset=48
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 offset_refcount_table_clusters=56
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+offset_nb_snapshots=60
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+offset_snapshots_offset=64
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 offset_header_size=100
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 offset_ext_magic=$header_size
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 offset_ext_size=$((header_size + 4))
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@@ -90,6 +92,31 @@ poke_file "$TEST_IMG" "$offset_refcount_table_offset" "\xff\xff\xff\xff\xff\xff\
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 poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x00\x00\x7f"
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 { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+echo
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+echo "== Invalid snapshot table =="
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+_make_test_img 64M
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+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\xff\xff\xff\xff"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x7f\xff\xff\xff"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+
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+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\xff\xff\xff\xff\xff\xff\x00\x00"
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+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x00\xff\xff"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+
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+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"
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+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x00\x00\x00"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+
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+echo
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+echo "== Hitting snapshot table size limit =="
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+_make_test_img 64M
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+# Put the refcount table in a more or less safe place (16 MB)
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+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\x00\x00\x00\x00\x01\x00\x00\x00"
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+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x01\x00\x00"
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+{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_testdir
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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/080.out b/tests/qemu-iotests/080.out
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index f919b58..b06f47f 100644
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--- a/tests/qemu-iotests/080.out
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+++ b/tests/qemu-iotests/080.out
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@@ -30,4 +30,21 @@ no file open, try 'help open'
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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.qcow2: Invalid reference count table offset
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 no file open, try 'help open'
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+
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+== Invalid snapshot table ==
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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.qcow2: Too many snapshots
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+no file open, try 'help open'
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+qemu-io: can't open device TEST_DIR/t.qcow2: Too many snapshots
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+no file open, try 'help open'
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+qemu-io: can't open device TEST_DIR/t.qcow2: Invalid snapshot table offset
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+no file open, try 'help open'
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+qemu-io: can't open device TEST_DIR/t.qcow2: Invalid snapshot table offset
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+no file open, try 'help open'
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+
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+== Hitting snapshot table size limit ==
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+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
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+qemu-img: Could not create snapshot 'test': -27 (File too large)
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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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 *** done
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-- 
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1.7.1
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