Patchwork [for-2.0,12/47] bochs: Check extent_size header field (CVE-2014-0142)

login
register
mail settings
Submitter Stefan Hajnoczi
Date March 26, 2014, 12:05 p.m.
Message ID <1395835569-21193-13-git-send-email-stefanha@redhat.com>
Download mbox | patch
Permalink /patch/333888/
State New
Headers show

Comments

Stefan Hajnoczi - March 26, 2014, 12:05 p.m.
From: Kevin Wolf <kwolf@redhat.com>

This fixes two possible division by zero crashes: In bochs_open() and in
seek_to_sector().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/bochs.c              |  8 ++++++++
 tests/qemu-iotests/078     | 13 +++++++++++++
 tests/qemu-iotests/078.out |  8 ++++++++
 3 files changed, 29 insertions(+)
Max Reitz - March 26, 2014, 8:13 p.m.
On 26.03.2014 13:05, Stefan Hajnoczi wrote:
> From: Kevin Wolf <kwolf@redhat.com>
>
> This fixes two possible division by zero crashes: In bochs_open() and in
> seek_to_sector().
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>   block/bochs.c              |  8 ++++++++
>   tests/qemu-iotests/078     | 13 +++++++++++++
>   tests/qemu-iotests/078.out |  8 ++++++++
>   3 files changed, 29 insertions(+)
>
> diff --git a/block/bochs.c b/block/bochs.c
> index 0ffa9c1..a922782 100644
> --- a/block/bochs.c
> +++ b/block/bochs.c
> @@ -148,6 +148,14 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
>       s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
>   
>       s->extent_size = le32_to_cpu(bochs.extent);
> +    if (s->extent_size == 0) {
> +        error_setg(errp, "Extent size may not be zero");
> +        return -EINVAL;
> +    } else if (s->extent_size > 0x800000) {
> +        error_setg(errp, "Extent size %" PRIu32 " is too large",

Hm. *g*

> +                   s->extent_size);
> +        return -EINVAL;
> +    }
>   
>       if (s->catalog_size < bs->total_sectors / s->extent_size) {
>           error_setg(errp, "Catalog size is too small for this disk size");
> diff --git a/tests/qemu-iotests/078 b/tests/qemu-iotests/078
> index 902ef0f..872e734 100755
> --- a/tests/qemu-iotests/078
> +++ b/tests/qemu-iotests/078
> @@ -43,6 +43,7 @@ _supported_proto generic
>   _supported_os Linux
>   
>   catalog_size_offset=$((0x48))
> +extent_size_offset=$((0x50))
>   disk_size_offset=$((0x58))
>   
>   echo
> @@ -68,6 +69,18 @@ _use_sample_img empty.bochs.bz2
>   poke_file "$TEST_IMG" "$disk_size_offset" "\x00\xc0\x0f\x00\x00\x00\x00\x7f"
>   { $QEMU_IO -c "read 2T 4k" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
>   
> +echo
> +echo "== Negative extent size =="
> +_use_sample_img empty.bochs.bz2
> +poke_file "$TEST_IMG" "$extent_size_offset" "\xff\xff\xff\xff"
> +{ $QEMU_IO -c "read 768k 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
> +
> +echo
> +echo "== Zero extent size =="
> +_use_sample_img empty.bochs.bz2
> +poke_file "$TEST_IMG" "$extent_size_offset" "\x00\x00\x00\x00"
> +{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
> +
>   # success, all done
>   echo "*** done"
>   rm -f $seq.full
> diff --git a/tests/qemu-iotests/078.out b/tests/qemu-iotests/078.out
> index 7254693..ea95ffd 100644
> --- a/tests/qemu-iotests/078.out
> +++ b/tests/qemu-iotests/078.out
> @@ -15,4 +15,12 @@ no file open, try 'help open'
>   == Too small catalog bitmap for image size ==
>   qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size
>   no file open, try 'help open'
> +
> +== Negative extent size ==
> +qemu-io: can't open device TEST_DIR/empty.bochs: Extent size 4294967295 is too large
> +no file open, try 'help open'
> +
> +== Zero extent size ==
> +qemu-io: can't open device TEST_DIR/empty.bochs: Extent size may not be zero
> +no file open, try 'help open'
>   *** done

Reviewed-by: Max Reitz <mreitz@redhat.com>

Patch

diff --git a/block/bochs.c b/block/bochs.c
index 0ffa9c1..a922782 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -148,6 +148,14 @@  static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
     s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
 
     s->extent_size = le32_to_cpu(bochs.extent);
+    if (s->extent_size == 0) {
+        error_setg(errp, "Extent size may not be zero");
+        return -EINVAL;
+    } else if (s->extent_size > 0x800000) {
+        error_setg(errp, "Extent size %" PRIu32 " is too large",
+                   s->extent_size);
+        return -EINVAL;
+    }
 
     if (s->catalog_size < bs->total_sectors / s->extent_size) {
         error_setg(errp, "Catalog size is too small for this disk size");
diff --git a/tests/qemu-iotests/078 b/tests/qemu-iotests/078
index 902ef0f..872e734 100755
--- a/tests/qemu-iotests/078
+++ b/tests/qemu-iotests/078
@@ -43,6 +43,7 @@  _supported_proto generic
 _supported_os Linux
 
 catalog_size_offset=$((0x48))
+extent_size_offset=$((0x50))
 disk_size_offset=$((0x58))
 
 echo
@@ -68,6 +69,18 @@  _use_sample_img empty.bochs.bz2
 poke_file "$TEST_IMG" "$disk_size_offset" "\x00\xc0\x0f\x00\x00\x00\x00\x7f"
 { $QEMU_IO -c "read 2T 4k" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
 
+echo
+echo "== Negative extent size =="
+_use_sample_img empty.bochs.bz2
+poke_file "$TEST_IMG" "$extent_size_offset" "\xff\xff\xff\xff"
+{ $QEMU_IO -c "read 768k 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+
+echo
+echo "== Zero extent size =="
+_use_sample_img empty.bochs.bz2
+poke_file "$TEST_IMG" "$extent_size_offset" "\x00\x00\x00\x00"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/078.out b/tests/qemu-iotests/078.out
index 7254693..ea95ffd 100644
--- a/tests/qemu-iotests/078.out
+++ b/tests/qemu-iotests/078.out
@@ -15,4 +15,12 @@  no file open, try 'help open'
 == Too small catalog bitmap for image size ==
 qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size
 no file open, try 'help open'
+
+== Negative extent size ==
+qemu-io: can't open device TEST_DIR/empty.bochs: Extent size 4294967295 is too large
+no file open, try 'help open'
+
+== Zero extent size ==
+qemu-io: can't open device TEST_DIR/empty.bochs: Extent size may not be zero
+no file open, try 'help open'
 *** done