From 509a41bab5306181044b5fff02eadf96d9c8676a Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 26 Mar 2014 13:05:26 +0100 Subject: block/cloop: prevent offsets_size integer overflow (CVE-2014-0143) The following integer overflow in offsets_size can lead to out-of-bounds memory stores when n_blocks has a huge value: uint32_t n_blocks, offsets_size; [...] ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4); [...] s->n_blocks = be32_to_cpu(s->n_blocks); /* read offsets */ offsets_size = s->n_blocks * sizeof(uint64_t); s->offsets = g_malloc(offsets_size); [...] for(i=0;in_blocks;i++) { s->offsets[i] = be64_to_cpu(s->offsets[i]); offsets_size can be smaller than n_blocks due to integer overflow. Therefore s->offsets[] is too small when the for loop byteswaps offsets. This patch refuses to open files if offsets_size would overflow. Note that changing the type of offsets_size is not a fix since 32-bit hosts still only have 32-bit size_t. Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Signed-off-by: Stefan Hajnoczi --- tests/qemu-iotests/075 | 7 +++++++ tests/qemu-iotests/075.out | 4 ++++ 2 files changed, 11 insertions(+) (limited to 'tests/qemu-iotests') diff --git a/tests/qemu-iotests/075 b/tests/qemu-iotests/075 index 8f54a99..9ce6b1f 100755 --- a/tests/qemu-iotests/075 +++ b/tests/qemu-iotests/075 @@ -43,6 +43,7 @@ _supported_proto generic _supported_os Linux block_size_offset=128 +n_blocks_offset=132 echo echo "== check that the first sector can be read ==" @@ -67,6 +68,12 @@ _use_sample_img simple-pattern.cloop.bz2 poke_file "$TEST_IMG" "$block_size_offset" "\xff\xff\xfe\x00" $QEMU_IO -c "read 0 512" $TEST_IMG 2>&1 | _filter_qemu_io | _filter_testdir +echo +echo "== offsets_size overflow ===" +_use_sample_img simple-pattern.cloop.bz2 +poke_file "$TEST_IMG" "$n_blocks_offset" "\xff\xff\xff\xff" +$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/075.out b/tests/qemu-iotests/075.out index d362c95..a771789 100644 --- a/tests/qemu-iotests/075.out +++ b/tests/qemu-iotests/075.out @@ -15,4 +15,8 @@ no file open, try 'help open' == huge block_size === qemu-io: can't open device TEST_DIR/simple-pattern.cloop: block_size 4294966784 must be 64 MB or less no file open, try 'help open' + +== offsets_size overflow === +qemu-io: can't open device TEST_DIR/simple-pattern.cloop: n_blocks 4294967295 must be 536870911 or less +no file open, try 'help open' *** done -- cgit v1.1