[Qemu-devel] [PATCH v2 1/2] qcow2: Make size_to_clusters() return uint64_t

[Max Reitz]

Sadly, some images may have more clusters than what can be represented
using a plain int. We should be prepared for that case (in
qcow2_check_refcounts() we actually were trying to catch that case, but
since size_to_clusters() truncated the returned value, that check never
did anything useful).

Cc: qemu-stable <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
---
 block/qcow2-cluster.c  | 30 +++++++++++++++++++-----------
 block/qcow2-refcount.c | 10 +++++++---
 block/qcow2.h          |  6 +++---
 3 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 2975b83..dc217e7 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -298,7 +298,7 @@ fail:
  * as contiguous. (This allows it, for example, to stop at the first compressed
  * cluster which may require a different handling)
  */
-static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size,
+static int count_contiguous_clusters(int nb_clusters, int cluster_size,
         uint64_t *l2_table, uint64_t stop_flags)
 {
     int i;
@@ -321,7 +321,7 @@ static int count_contiguous_clusters(uint64_t nb_clusters, 
int cluster_size,
        return i;
 }
 
-static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t 
*l2_table)
+static int count_contiguous_free_clusters(int nb_clusters, uint64_t *l2_table)
 {
     int i;
 
@@ -495,6 +495,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t 
offset,
     if (nb_needed > nb_available) {
         nb_needed = nb_available;
     }
+    assert(nb_needed <= INT_MAX);
 
     *cluster_offset = 0;
 
@@ -530,6 +531,8 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t 
offset,
 
     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
     *cluster_offset = be64_to_cpu(l2_table[l2_index]);
+
+    /* nb_needed <= INT_MAX, thus nb_clusters <= INT_MAX, too */
     nb_clusters = size_to_clusters(s, nb_needed << 9);
 
     ret = qcow2_get_cluster_type(*cluster_offset);
@@ -840,7 +843,7 @@ err:
 static int count_cow_clusters(BDRVQcow2State *s, int nb_clusters,
     uint64_t *l2_table, int l2_index)
 {
-    int i;
+    uint64_t i;
 
     for (i = 0; i < nb_clusters; i++) {
         uint64_t l2_entry = be64_to_cpu(l2_table[l2_index + i]);
@@ -960,7 +963,7 @@ static int handle_copied(BlockDriverState *bs, uint64_t 
guest_offset,
     int l2_index;
     uint64_t cluster_offset;
     uint64_t *l2_table;
-    unsigned int nb_clusters;
+    uint64_t nb_clusters;
     unsigned int keep_clusters;
     int ret;
 
@@ -979,6 +982,7 @@ static int handle_copied(BlockDriverState *bs, uint64_t 
guest_offset,
 
     l2_index = offset_to_l2_index(s, guest_offset);
     nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+    assert(nb_clusters <= INT_MAX);
 
     /* Find L2 entry for the first involved cluster */
     ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index);
@@ -1061,7 +1065,7 @@ out:
  * restarted, but the whole request should not be failed.
  */
 static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
-    uint64_t *host_offset, unsigned int *nb_clusters)
+                                   uint64_t *host_offset, uint64_t 
*nb_clusters)
 {
     BDRVQcow2State *s = bs->opaque;
 
@@ -1079,7 +1083,7 @@ static int do_alloc_cluster_offset(BlockDriverState *bs, 
uint64_t guest_offset,
         *host_offset = cluster_offset;
         return 0;
     } else {
-        int ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
+        int64_t ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
         if (ret < 0) {
             return ret;
         }
@@ -1115,7 +1119,7 @@ static int handle_alloc(BlockDriverState *bs, uint64_t 
guest_offset,
     int l2_index;
     uint64_t *l2_table;
     uint64_t entry;
-    unsigned int nb_clusters;
+    uint64_t nb_clusters;
     int ret;
 
     uint64_t alloc_cluster_offset;
@@ -1133,6 +1137,7 @@ static int handle_alloc(BlockDriverState *bs, uint64_t 
guest_offset,
 
     l2_index = offset_to_l2_index(s, guest_offset);
     nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+    assert(nb_clusters <= INT_MAX);
 
     /* Find L2 entry for the first involved cluster */
     ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index);
@@ -1426,7 +1431,8 @@ int qcow2_decompress_cluster(BlockDriverState *bs, 
uint64_t cluster_offset)
  * clusters.
  */
 static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
-    unsigned int nb_clusters, enum qcow2_discard_type type, bool full_discard)
+                             uint64_t nb_clusters, enum qcow2_discard_type 
type,
+                             bool full_discard)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t *l2_table;
@@ -1441,6 +1447,7 @@ static int discard_single_l2(BlockDriverState *bs, 
uint64_t offset,
 
     /* Limit nb_clusters to one L2 table */
     nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+    assert(nb_clusters <= INT_MAX);
 
     for (i = 0; i < nb_clusters; i++) {
         uint64_t old_l2_entry;
@@ -1503,7 +1510,7 @@ int qcow2_discard_clusters(BlockDriverState *bs, uint64_t 
offset,
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t end_offset;
-    unsigned int nb_clusters;
+    uint64_t nb_clusters;
     int ret;
 
     end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS);
@@ -1545,7 +1552,7 @@ fail:
  * clusters.
  */
 static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
-    unsigned int nb_clusters)
+                          uint64_t nb_clusters)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t *l2_table;
@@ -1560,6 +1567,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t 
offset,
 
     /* Limit nb_clusters to one L2 table */
     nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
+    assert(nb_clusters <= INT_MAX);
 
     for (i = 0; i < nb_clusters; i++) {
         uint64_t old_offset;
@@ -1584,7 +1592,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t 
offset,
 int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors)
 {
     BDRVQcow2State *s = bs->opaque;
-    unsigned int nb_clusters;
+    uint64_t nb_clusters;
     int ret;
 
     /* The zero flag is only supported by version 3 and newer */
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 53e3e9f..e8430ec 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -875,8 +875,8 @@ int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t 
size)
     return offset;
 }
 
-int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
-    int nb_clusters)
+int64_t qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
+                                int64_t nb_clusters)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t cluster_index, refcount;
@@ -1259,7 +1259,7 @@ static size_t refcount_array_byte_size(BDRVQcow2State *s, 
uint64_t entries)
 static int realloc_refcount_array(BDRVQcow2State *s, void **array,
                                   int64_t *size, int64_t new_size)
 {
-    size_t old_byte_size, new_byte_size;
+    int64_t old_byte_size, new_byte_size;
     void *new_ptr;
 
     /* Round to clusters so the array can be directly written to disk */
@@ -1275,6 +1275,10 @@ static int realloc_refcount_array(BDRVQcow2State *s, 
void **array,
 
     assert(new_byte_size > 0);
 
+    if (new_byte_size > SIZE_MAX) {
+        return -ENOMEM;
+    }
+
     new_ptr = g_try_realloc(*array, new_byte_size);
     if (!new_ptr) {
         return -ENOMEM;
diff --git a/block/qcow2.h b/block/qcow2.h
index 61f1b57..d700bf1 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -415,7 +415,7 @@ static inline int64_t offset_into_cluster(BDRVQcow2State 
*s, int64_t offset)
     return offset & (s->cluster_size - 1);
 }
 
-static inline int size_to_clusters(BDRVQcow2State *s, int64_t size)
+static inline uint64_t size_to_clusters(BDRVQcow2State *s, uint64_t size)
 {
     return (size + (s->cluster_size - 1)) >> s->cluster_bits;
 }
@@ -509,8 +509,8 @@ int qcow2_update_cluster_refcount(BlockDriverState *bs, 
int64_t cluster_index,
                                   enum qcow2_discard_type type);
 
 int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t size);
-int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
-    int nb_clusters);
+int64_t qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
+                                int64_t nb_clusters);
 int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
 void qcow2_free_clusters(BlockDriverState *bs,
                           int64_t offset, int64_t size,
-- 
2.5.1