From 610ab7bd3d22dcd328eaabff1be627510bae23b5 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 26 Mar 2014 13:05:50 +0100 Subject: [PATCH] qcow2: Check new refcount table size on growth If the size becomes larger than what qcow2_open() would accept, fail the growing operation. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Signed-off-by: Stefan Hajnoczi (cherry picked from commit 2b5d5953eec0cc541857c3df812bdf8421596ab2) Signed-off-by: Michael Roth --- block/qcow2-refcount.c | 4 ++++ block/qcow2.c | 4 +--- block/qcow2.h | 9 +++++++++ 3 files changed, 14 insertions(+), 3 deletions(-) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 57c1fbad96..29e25a726c 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -310,6 +310,10 @@ static int alloc_refcount_block(BlockDriverState *bs, uint64_t refcount_block_clusters = 1 << (s->cluster_bits - REFCOUNT_SHIFT); uint64_t blocks_used = DIV_ROUND_UP(cluster_index, refcount_block_clusters); + if (blocks_used > QCOW_MAX_REFTABLE_SIZE / sizeof(uint64_t)) { + return -EFBIG; + } + /* And now we need at least one block more for the new metadata */ uint64_t table_size = next_refcount_table_size(s, blocks_used + 1); uint64_t last_table_size; diff --git a/block/qcow2.c b/block/qcow2.c index 45f3f8a10b..447308ea9f 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -611,9 +611,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, s->refcount_table_size = header.refcount_table_clusters << (s->cluster_bits - 3); - if (header.refcount_table_clusters > (0x800000 >> s->cluster_bits)) { - /* 8 MB refcount table is enough for 2 PB images at 64k cluster size - * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ + if (header.refcount_table_clusters > qcow2_max_refcount_clusters(s)) { error_setg(errp, "Reference count table too large"); ret = -EINVAL; goto fail; diff --git a/block/qcow2.h b/block/qcow2.h index 99fe092753..e1b4c4b846 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -40,6 +40,10 @@ #define QCOW_MAX_CRYPT_CLUSTERS 32 #define QCOW_MAX_SNAPSHOTS 65536 +/* 8 MB refcount table is enough for 2 PB images at 64k cluster size + * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */ +#define QCOW_MAX_REFTABLE_SIZE 0x800000 + /* indicate that the refcount of the referenced cluster is exactly one. */ #define QCOW_OFLAG_COPIED (1ULL << 63) /* indicate that the cluster is compressed (they never have the copied flag) */ @@ -410,6 +414,11 @@ static inline int64_t qcow2_vm_state_offset(BDRVQcowState *s) return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits); } +static inline uint64_t qcow2_max_refcount_clusters(BDRVQcowState *s) +{ + return QCOW_MAX_REFTABLE_SIZE >> s->cluster_bits; +} + static inline int qcow2_get_cluster_type(uint64_t l2_entry) { if (l2_entry & QCOW_OFLAG_COMPRESSED) {