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bochs: Check catalog_size header field (CVE-2014-0143)

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It should neither become negative nor allow unbounded memory
allocations. This fixes aborts in g_malloc() and an s->catalog_bitmap
buffer overflow on big endian hosts.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2014-03-26 13:05:33 +01:00 committed by Stefan Hajnoczi
parent 246f65838d
commit e3737b820b
3 changed files with 35 additions and 1 deletions
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13
block/bochs.c
View file

@ -123,7 +123,14 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
}
/* Limit to 1M entries to avoid unbounded allocation. This is what is
* needed for the largest image that bximage can create (~8 TB). */
s->catalog_size = le32_to_cpu(bochs.catalog);
if (s->catalog_size > 0x100000) {
error_setg(errp, "Catalog size is too large");
return -EFBIG;
}
s->catalog_bitmap = g_malloc(s->catalog_size * 4);
ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
@ -142,6 +149,12 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
s->extent_size = le32_to_cpu(bochs.extent);
if (s->catalog_size < bs->total_sectors / s->extent_size) {
error_setg(errp, "Catalog size is too small for this disk size");
ret = -EINVAL;
goto fail;
}
qemu_co_mutex_init(&s->lock);
return 0;

13
tests/qemu-iotests/078
View file

@ -43,6 +43,7 @@ _supported_proto generic
_supported_os Linux
catalog_size_offset=$((0x48))
disk_size_offset=$((0x58))
echo
echo "== Read from a valid image =="
@ -55,6 +56,18 @@ _use_sample_img empty.bochs.bz2
poke_file "$TEST_IMG" "$catalog_size_offset" "\xff\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Overflow for catalog size * sizeof(uint32_t) =="
_use_sample_img empty.bochs.bz2
poke_file "$TEST_IMG" "$catalog_size_offset" "\x00\x00\x00\x40"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Too small catalog bitmap for image size =="
_use_sample_img empty.bochs.bz2
poke_file "$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
# success, all done
echo "*** done"
rm -f $seq.full

10
tests/qemu-iotests/078.out
View file

@ -5,6 +5,14 @@ read 512/512 bytes at offset 0
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
== Negative catalog size ==
qemu-io: can't open device TEST_DIR/empty.bochs: Could not open 'TEST_DIR/empty.bochs': Interrupted system call
qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too large
no file open, try 'help open'
== Overflow for catalog size * sizeof(uint32_t) ==
qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too large
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'
*** done