linux-kernel - [PATCH v2 08/24] virtio-mem: use vmalloc

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Date:   Tue, 27 Jun 2023 16:43:23 +0200
From:   Julia Lawall <Julia.Lawall@...ia.fr>
To:     David Hildenbrand <david@...hat.com>
Cc:     kernel-janitors@...r.kernel.org, keescook@...omium.org,
        christophe.jaillet@...adoo.fr, kuba@...nel.org,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 08/24] virtio-mem: use vmalloc_array and vcalloc

Use vmalloc_array and vcalloc to protect against
multiplication overflows.

The changes were done using the following Coccinelle
semantic patch:

// <smpl>
@initialize:ocaml@
@@

let rename alloc =
  match alloc with
    "vmalloc" -> "vmalloc_array"
  | "vzalloc" -> "vcalloc"
  | _ -> failwith "unknown"

@@
    size_t e1,e2;
    constant C1, C2;
    expression E1, E2, COUNT, x1, x2, x3;
    typedef u8;
    typedef __u8;
    type t = {u8,__u8,char,unsigned char};
    identifier alloc = {vmalloc,vzalloc};
    fresh identifier realloc = script:ocaml(alloc) { rename alloc };
@@

(
      alloc(x1*x2*x3)
|
      alloc(C1 * C2)
|
      alloc((sizeof(t)) * (COUNT), ...)
|
-     alloc((e1) * (e2))
+     realloc(e1, e2)
|
-     alloc((e1) * (COUNT))
+     realloc(COUNT, e1)
|
-     alloc((E1) * (E2))
+     realloc(E1, E2)
)
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@...ia.fr>

---
v2: Use vmalloc_array and vcalloc instead of array_size.
This also leaves a multiplication of a constant by a sizeof
as is.  Two patches are thus dropped from the series.

 drivers/virtio/virtio_mem.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff -u -p a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -399,7 +399,7 @@ static int virtio_mem_bbm_bb_states_prep
 	if (vm->bbm.bb_states && old_pages == new_pages)
 		return 0;
 
-	new_array = vzalloc(new_pages * PAGE_SIZE);
+	new_array = vcalloc(new_pages, PAGE_SIZE);
 	if (!new_array)
 		return -ENOMEM;
 
@@ -465,7 +465,7 @@ static int virtio_mem_sbm_mb_states_prep
 	if (vm->sbm.mb_states && old_pages == new_pages)
 		return 0;
 
-	new_array = vzalloc(new_pages * PAGE_SIZE);
+	new_array = vcalloc(new_pages, PAGE_SIZE);
 	if (!new_array)
 		return -ENOMEM;
 
@@ -588,7 +588,7 @@ static int virtio_mem_sbm_sb_states_prep
 	if (vm->sbm.sb_states && old_pages == new_pages)
 		return 0;
 
-	new_bitmap = vzalloc(new_pages * PAGE_SIZE);
+	new_bitmap = vcalloc(new_pages, PAGE_SIZE);
 	if (!new_bitmap)
 		return -ENOMEM;