Drivers: hv: hv_balloon: correctly handle num_pages>INT_MAX case

balloon_wrk.num_pages is __u32 and it comes from host in struct dm_balloon
where it is also __u32. We, however, use 'int' in balloon_up() and in case
we happen to receive num_pages>INT_MAX request we'll end up allocating zero
pages as 'num_pages < alloc_unit' check in alloc_balloon_pages() will pass.
Change num_pages type to unsigned int.

In real life ballooning request come with num_pages in [512, 32768] range so
this is more a future-proof/cleanup.

Reported-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 4052ad8255fa..cb5b7dc9797f 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -1081,11 +1081,12 @@ static void free_balloon_pages(struct hv_dynmem_device *dm,
 
 
 
-static int alloc_balloon_pages(struct hv_dynmem_device *dm, int num_pages,
-                               struct dm_balloon_response *bl_resp,
-                               int alloc_unit)
+static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
+                                        unsigned int num_pages,
+                                        struct dm_balloon_response *bl_resp,
+                                        int alloc_unit)
 {
-        int i = 0;
+        unsigned int i = 0;
         struct page *pg;
 
         if (num_pages < alloc_unit)
@@ -1132,8 +1133,8 @@ static int alloc_balloon_pages(struct hv_dynmem_device *dm, int num_pages,
 
 static void balloon_up(struct work_struct *dummy)
 {
-        int num_pages = dm_device.balloon_wrk.num_pages;
-        int num_ballooned = 0;
+        unsigned int num_pages = dm_device.balloon_wrk.num_pages;
+        unsigned int num_ballooned = 0;
         struct dm_balloon_response *bl_resp;
         int alloc_unit;
         int ret;