linux-kernel - [PATCH v2 20/24] comedi: use vmalloc

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Message-Id: <20230627144339.144478-21-Julia.Lawall@inria.fr>
Date:   Tue, 27 Jun 2023 16:43:35 +0200
From:   Julia Lawall <Julia.Lawall@...ia.fr>
To:     Ian Abbott <abbotti@....co.uk>
Cc:     kernel-janitors@...r.kernel.org, keescook@...omium.org,
        christophe.jaillet@...adoo.fr, kuba@...nel.org,
        H Hartley Sweeten <hsweeten@...ionengravers.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 20/24] comedi: 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.  The position of this patch in the series changed
accordingly.

 drivers/comedi/comedi_buf.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -u -p a/drivers/comedi/comedi_buf.c b/drivers/comedi/comedi_buf.c
--- a/drivers/comedi/comedi_buf.c
+++ b/drivers/comedi/comedi_buf.c
@@ -89,7 +89,7 @@ comedi_buf_map_alloc(struct comedi_devic
 		bm->dma_hw_dev = get_device(dev->hw_dev);
 	}
 
-	bm->page_list = vzalloc(sizeof(*buf) * n_pages);
+	bm->page_list = vcalloc(n_pages, sizeof(*buf));
 	if (!bm->page_list)
 		goto err;
 
@@ -169,7 +169,7 @@ static void __comedi_buf_alloc(struct co
 		buf = &bm->page_list[0];
 		async->prealloc_buf = buf->virt_addr;
 	} else {
-		pages = vmalloc(sizeof(struct page *) * n_pages);
+		pages = vmalloc_array(n_pages, sizeof(struct page *));
 		if (!pages)
 			return;