RDMA/uverbs: Fix incorrect variable type

Fix incorrect type of max_entries in UVERBS_METHOD_QUERY_GID_TABLE -
max_entries is of type size_t although it can take negative values.

The following static check revealed it:

drivers/infiniband/core/uverbs_std_types_device.c:338 ib_uverbs_handler_UVERBS_METHOD_QUERY_GID_TABLE() warn: 'max_entries' unsigned <= 0

Fixes: 9f85cbe5 ("RDMA/uverbs: Expose the new GID query API to user space")
Link: https://lore.kernel.org/r/20201208073545.9723-4-leon@kernel.orgReported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/uverbs_std_types_device.c

@@ -317,8 +317,7 @@ static int UVERBS_HANDLER(UVERBS_METHOD_QUERY_GID_TABLE)(
 	struct ib_device *ib_dev;
 	size_t user_entry_size;
 	ssize_t num_entries;
-	size_t max_entries;
-	size_t num_bytes;
+	int max_entries;
 	u32 flags;
 	int ret;
 
@@ -336,19 +335,16 @@ static int UVERBS_HANDLER(UVERBS_METHOD_QUERY_GID_TABLE)(
 		attrs, UVERBS_ATTR_QUERY_GID_TABLE_RESP_ENTRIES,
 		user_entry_size);
 	if (max_entries <= 0)
-		return -EINVAL;
+		return max_entries ?: -EINVAL;
 
 	ucontext = ib_uverbs_get_ucontext(attrs);
 	if (IS_ERR(ucontext))
 		return PTR_ERR(ucontext);
 	ib_dev = ucontext->device;
 
-	if (check_mul_overflow(max_entries, sizeof(*entries), &num_bytes))
-		return -EINVAL;
-
-	entries = uverbs_zalloc(attrs, num_bytes);
-	if (!entries)
-		return -ENOMEM;
+	entries = uverbs_kcalloc(attrs, max_entries, sizeof(*entries));
+	if (IS_ERR(entries))
+		return PTR_ERR(entries);
 
 	num_entries = rdma_query_gid_table(ib_dev, entries, max_entries);
 	if (num_entries < 0)

include/rdma/uverbs_ioctl.h

@@ -865,6 +865,16 @@ static inline __malloc void *uverbs_zalloc(struct uverbs_attr_bundle *bundle,
 {
 	return _uverbs_alloc(bundle, size, GFP_KERNEL | __GFP_ZERO);
 }
+
+static inline __malloc void *uverbs_kcalloc(struct uverbs_attr_bundle *bundle,
+					    size_t n, size_t size)
+{
+	size_t bytes;
+
+	if (unlikely(check_mul_overflow(n, size, &bytes)))
+		return ERR_PTR(-EOVERFLOW);
+	return uverbs_zalloc(bundle, bytes);
+}
 int _uverbs_get_const(s64 *to, const struct uverbs_attr_bundle *attrs_bundle,
 		      size_t idx, s64 lower_bound, u64 upper_bound,
 		      s64 *def_val);