linux-kernel - [PATCH v2 06/24] dma-buf: system_heap: use vmalloc

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Date:   Tue, 27 Jun 2023 16:43:21 +0200
From:   Julia Lawall <Julia.Lawall@...ia.fr>
To:     Sumit Semwal <sumit.semwal@...aro.org>
Cc:     kernel-janitors@...r.kernel.org, keescook@...omium.org,
        christophe.jaillet@...adoo.fr, kuba@...nel.org,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>,
        Liam Mark <lmark@...eaurora.org>,
        Laura Abbott <labbott@...hat.com>,
        Brian Starkey <Brian.Starkey@....com>,
        John Stultz <jstultz@...gle.com>,
        Christian König <christian.koenig@....com>,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 06/24] dma-buf: system_heap: 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/dma-buf/heaps/system_heap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -u -p a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -221,7 +221,7 @@ static void *system_heap_do_vmap(struct
 {
 	struct sg_table *table = &buffer->sg_table;
 	int npages = PAGE_ALIGN(buffer->len) / PAGE_SIZE;
-	struct page **pages = vmalloc(sizeof(struct page *) * npages);
+	struct page **pages = vmalloc_array(npages, sizeof(struct page *));
 	struct page **tmp = pages;
 	struct sg_page_iter piter;
 	void *vaddr;