[Qemu-devel] [PATCH v3 2/4] block: Use g_new() & friends to avoid multiplying sizes

[Markus Armbruster]

g_new(T, n) is safer than g_malloc(sizeof(*v) * n) for two reasons.
One, it catches multiplication overflowing size_t.  Two, it returns
T * rather than void *, which lets the compiler catch more type
errors.

Perhaps a conversion to g_malloc_n() would be neater in places, but
that's merely four years old, and we can't use such newfangled stuff.

This commit only touches allocations with size arguments of the form
sizeof(T), plus two that use 4 instead of sizeof(uint32_t).  We can
make the others safe by converting to g_malloc_n() when it becomes
available to us in a couple of years.

Signed-off-by: Markus Armbruster <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
Reviewed-by: Jeff Cody <address@hidden>
---
 block/bochs.c       |  2 +-
 block/parallels.c   |  2 +-
 block/qcow2-cache.c |  2 +-
 block/qed-check.c   |  3 +--
 block/rbd.c         |  2 +-
 block/sheepdog.c    |  2 +-
 hw/block/nvme.c     |  8 ++++----
 qemu-io-cmds.c      | 10 +++++-----
 8 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/block/bochs.c b/block/bochs.c
index 6674b27..199ac2b 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -131,7 +131,7 @@ static int bochs_open(BlockDriverState *bs, QDict *options, 
int flags,
         return -EFBIG;
     }
 
-    s->catalog_bitmap = g_try_malloc(s->catalog_size * 4);
+    s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
     if (s->catalog_size && s->catalog_bitmap == NULL) {
         error_setg(errp, "Could not allocate memory for catalog");
         return -ENOMEM;
diff --git a/block/parallels.c b/block/parallels.c
index 1774ab8..2a814f3 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -121,7 +121,7 @@ static int parallels_open(BlockDriverState *bs, QDict 
*options, int flags,
         ret = -EFBIG;
         goto fail;
     }
-    s->catalog_bitmap = g_try_malloc(s->catalog_size * 4);
+    s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
     if (s->catalog_size && s->catalog_bitmap == NULL) {
         ret = -ENOMEM;
         goto fail;
diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 5353b44..fe0615a 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -50,7 +50,7 @@ Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int 
num_tables)
 
     c = g_malloc0(sizeof(*c));
     c->size = num_tables;
-    c->entries = g_malloc0(sizeof(*c->entries) * num_tables);
+    c->entries = g_new0(Qcow2CachedTable, num_tables);
 
     for (i = 0; i < c->size; i++) {
         c->entries[i].table = qemu_try_blockalign(bs->file, s->cluster_size);
diff --git a/block/qed-check.c b/block/qed-check.c
index 40a882c..36ecd29 100644
--- a/block/qed-check.c
+++ b/block/qed-check.c
@@ -227,8 +227,7 @@ int qed_check(BDRVQEDState *s, BdrvCheckResult *result, 
bool fix)
     };
     int ret;
 
-    check.used_clusters = g_try_malloc0(((check.nclusters + 31) / 32) *
-                                        sizeof(check.used_clusters[0]));
+    check.used_clusters = g_try_new0(uint32_t, (check.nclusters + 31) / 32);
     if (check.nclusters && check.used_clusters == NULL) {
         return -ENOMEM;
     }
diff --git a/block/rbd.c b/block/rbd.c
index 3aaf855..ea969e7 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -862,7 +862,7 @@ static int qemu_rbd_snap_list(BlockDriverState *bs,
     int max_snaps = RBD_MAX_SNAPS;
 
     do {
-        snaps = g_malloc(sizeof(*snaps) * max_snaps);
+        snaps = g_new(rbd_snap_info_t, max_snaps);
         snap_count = rbd_snap_list(s->image, snaps, &max_snaps);
         if (snap_count <= 0) {
             g_free(snaps);
diff --git a/block/sheepdog.c b/block/sheepdog.c
index ba1ef43..12cbd9d 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -2357,7 +2357,7 @@ static int sd_snapshot_list(BlockDriverState *bs, 
QEMUSnapshotInfo **psn_tab)
         goto out;
     }
 
-    sn_tab = g_malloc0(nr * sizeof(*sn_tab));
+    sn_tab = g_new0(QEMUSnapshotInfo, nr);
 
     /* calculate a vdi id with hash function */
     hval = fnv_64a_buf(s->name, strlen(s->name), FNV1A_64_INIT);
diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 5fd8f89..47577ec 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -319,7 +319,7 @@ static void nvme_init_sq(NvmeSQueue *sq, NvmeCtrl *n, 
uint64_t dma_addr,
     sq->size = size;
     sq->cqid = cqid;
     sq->head = sq->tail = 0;
-    sq->io_req = g_malloc(sq->size * sizeof(*sq->io_req));
+    sq->io_req = g_new(NvmeRequest, sq->size);
 
     QTAILQ_INIT(&sq->req_list);
     QTAILQ_INIT(&sq->out_req_list);
@@ -773,9 +773,9 @@ static int nvme_init(PCIDevice *pci_dev)
     n->reg_size = 1 << qemu_fls(0x1004 + 2 * (n->num_queues + 1) * 4);
     n->ns_size = bs_size / (uint64_t)n->num_namespaces;
 
-    n->namespaces = g_malloc0(sizeof(*n->namespaces)*n->num_namespaces);
-    n->sq = g_malloc0(sizeof(*n->sq)*n->num_queues);
-    n->cq = g_malloc0(sizeof(*n->cq)*n->num_queues);
+    n->namespaces = g_new0(NvmeNamespace, n->num_namespaces);
+    n->sq = g_new0(NvmeSQueue *, n->num_queues);
+    n->cq = g_new0(NvmeCQueue *, n->num_queues);
 
     memory_region_init_io(&n->iomem, OBJECT(n), &nvme_mmio_ops, n,
                           "nvme", n->reg_size);
diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 3a1e11e..afd8867 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -29,7 +29,7 @@ static int compare_cmdname(const void *a, const void *b)
 
 void qemuio_add_command(const cmdinfo_t *ci)
 {
-    cmdtab = g_realloc(cmdtab, ++ncmds * sizeof(*cmdtab));
+    cmdtab = g_renew(cmdinfo_t, cmdtab, ++ncmds);
     cmdtab[ncmds - 1] = *ci;
     qsort(cmdtab, ncmds, sizeof(*cmdtab), compare_cmdname);
 }
@@ -122,7 +122,7 @@ static char **breakline(char *input, int *count)
             continue;
         }
         c++;
-        tmp = g_realloc(rval, sizeof(*rval) * (c + 1));
+        tmp = g_renew(char *, rval, (c + 1));
         if (!tmp) {
             g_free(rval);
             rval = NULL;
@@ -1264,9 +1264,9 @@ static int multiwrite_f(BlockDriverState *bs, int argc, 
char **argv)
         }
     }
 
-    reqs = g_malloc0(nr_reqs * sizeof(*reqs));
-    buf = g_malloc0(nr_reqs * sizeof(*buf));
-    qiovs = g_malloc(nr_reqs * sizeof(*qiovs));
+    reqs = g_new0(BlockRequest, nr_reqs);
+    buf = g_new0(char *, nr_reqs);
+    qiovs = g_new(QEMUIOVector, nr_reqs);
 
     for (i = 0; i < nr_reqs && optind < argc; i++) {
         int j;
-- 
1.9.3