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Blame SOURCES/kvm-block-cloop-refuse-images-with-huge-offsets-arrays-C.patch

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From 54e639827c618c74ecb47690754f0299c2e35750 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 14:23:13 +0100
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Subject: [PATCH 06/49] block/cloop: refuse images with huge offsets arrays (CVE-2014-0144)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-7-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 06/48] block/cloop: refuse images with huge offsets arrays (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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Limit offsets_size to 512 MB so that:
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1. g_malloc() does not abort due to an unreasonable size argument.
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2. offsets_size does not overflow the bdrv_pread() int size argument.
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This limit imposes a maximum image size of 16 TB at 256 KB block size.
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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              |    9 +++++++++
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 tests/qemu-iotests/075     |    6 ++++++
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 tests/qemu-iotests/075.out |    4 ++++
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 3 files changed, 19 insertions(+), 0 deletions(-)
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diff --git a/block/cloop.c b/block/cloop.c
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index 563e916..844665e 100644
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--- a/block/cloop.c
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+++ b/block/cloop.c
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@@ -107,6 +107,15 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
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         return -EINVAL;
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     }
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     offsets_size = s->n_blocks * sizeof(uint64_t);
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+    if (offsets_size > 512 * 1024 * 1024) {
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+        /* Prevent ridiculous offsets_size which causes memory allocation to
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+         * fail or overflows bdrv_pread() size.  In practice the 512 MB
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+         * offsets[] limit supports 16 TB images at 256 KB block size.
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+         */
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+        error_setg(errp, "image requires too many offsets, "
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+                   "try increasing block size");
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+        return -EINVAL;
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+    }
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     s->offsets = g_malloc(offsets_size);
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     ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size);
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diff --git a/tests/qemu-iotests/075 b/tests/qemu-iotests/075
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index 9ce6b1f..9c00fa8 100755
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--- a/tests/qemu-iotests/075
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+++ b/tests/qemu-iotests/075
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@@ -74,6 +74,12 @@ _use_sample_img simple-pattern.cloop.bz2
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 poke_file "$TEST_IMG" "$n_blocks_offset" "\xff\xff\xff\xff"
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 $QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
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+echo
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+echo "== refuse images that require too many offsets ==="
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+_use_sample_img simple-pattern.cloop.bz2
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+poke_file "$TEST_IMG" "$n_blocks_offset" "\x04\x00\x00\x01"
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+$QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir
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+
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 # 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 a771789..7cdaee1 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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@@ -19,4 +19,8 @@ no file open, try 'help open'
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 == offsets_size overflow ===
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 qemu-io: can't open device TEST_DIR/simple-pattern.cloop: n_blocks 4294967295 must be 536870911 or less
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 no file open, try 'help open'
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+
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+== refuse images that require too many offsets ===
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+qemu-io: can't open device TEST_DIR/simple-pattern.cloop: image requires too many offsets, try increasing block 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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