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From 86c71987b64382e1177f86e6bc00bfc19e20082d Mon Sep 17 00:00:00 2001
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From: Fam Zheng <famz@redhat.com>
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Date: Mon, 15 Feb 2016 09:28:18 +0100
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Subject: [PATCH 05/18] vmdk: Check descriptor file length when reading it
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RH-Author: Fam Zheng <famz@redhat.com>
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Message-id: <1455528511-9357-6-git-send-email-famz@redhat.com>
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Patchwork-id: 69171
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O-Subject: [RHEL-7.3 qemu-kvm PATCH 05/18] vmdk: Check descriptor file length when reading it
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Bugzilla: 1299250
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Markus Armbruster <armbru@redhat.com>
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BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1299250
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Since a too small file cannot be a valid VMDK image, and also since the
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buffer's first 4 bytes will be unconditionally examined by
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vmdk_open_sparse, let's error out the small file case to be clear.
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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Reviewed-by: Markus Armbruster <armbru@redhat.com>
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Reviewed-by: Don Koch <dkoch@verizon.com>
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Message-id: 1417649314-13704-5-git-send-email-famz@redhat.com
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 03c3359dfc490eaf922f88955d6a8cc51a37ce92)
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/vmdk.c | 8 ++++++++
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 1 file changed, 8 insertions(+)
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diff --git a/block/vmdk.c b/block/vmdk.c
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index 3dfbd41..db3cdc0 100644
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--- a/block/vmdk.c
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+++ b/block/vmdk.c
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@@ -559,6 +559,14 @@ static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
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         return NULL;
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     }
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+    if (size < 4) {
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+        /* Both descriptor file and sparse image must be much larger than 4
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+         * bytes, also callers of vmdk_read_desc want to compare the first 4
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+         * bytes with VMDK4_MAGIC, let's error out if less is read. */
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+        error_setg(errp, "File is too small, not a valid image");
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+        return NULL;
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+    }
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+
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     size = MIN(size, (1 << 20) - 1);  /* avoid unbounded allocation */
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     buf = g_malloc(size + 1);
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-- 
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1.8.3.1
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