From 46485de0cb357b57373e1ca895adedf1f3ed46ec Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Thu, 8 May 2014 13:08:20 +0200 Subject: [PATCH] qcow1: Validate image size (CVE-2014-0223) A huge image size could cause s->l1_size to overflow. Make sure that images never require a L1 table larger than what fits in s->l1_size. This cannot only cause unbounded allocations, but also the allocation of a too small L1 table, resulting in out-of-bounds array accesses (both reads and writes). Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf --- block/qcow.c | 16 ++++++++++++++-- tests/qemu-iotests/092 | 9 +++++++++ tests/qemu-iotests/092.out | 7 +++++++ 3 files changed, 30 insertions(+), 2 deletions(-) diff --git a/block/qcow.c b/block/qcow.c index e8038e5..3566c05 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -61,7 +61,7 @@ typedef struct BDRVQcowState { int cluster_sectors; int l2_bits; int l2_size; - int l1_size; + unsigned int l1_size; uint64_t cluster_offset_mask; uint64_t l1_table_offset; uint64_t *l1_table; @@ -166,7 +166,19 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags, /* read the level 1 table */ shift = s->cluster_bits + s->l2_bits; - s->l1_size = (header.size + (1LL << shift) - 1) >> shift; + if (header.size > UINT64_MAX - (1LL << shift)) { + error_setg(errp, "Image too large"); + ret = -EINVAL; + goto fail; + } else { + uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift; + if (l1_size > INT_MAX / sizeof(uint64_t)) { + error_setg(errp, "Image too large"); + ret = -EINVAL; + goto fail; + } + s->l1_size = l1_size; + } s->l1_table_offset = header.l1_table_offset; s->l1_table = g_malloc(s->l1_size * sizeof(uint64_t)); -- 1.9.3