linux-kernel - [PATCH v2 17/24] kcov: use vmalloc

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Message-Id: <20230627144339.144478-18-Julia.Lawall@inria.fr>
Date:   Tue, 27 Jun 2023 16:43:32 +0200
From:   Julia Lawall <Julia.Lawall@...ia.fr>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     kernel-janitors@...r.kernel.org, keescook@...omium.org,
        christophe.jaillet@...adoo.fr, kuba@...nel.org,
        Andrey Konovalov <andreyknvl@...il.com>,
        kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org
Subject: [PATCH v2 17/24] kcov: 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.

 kernel/kcov.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -u -p a/kernel/kcov.c b/kernel/kcov.c
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -901,7 +901,7 @@ void kcov_remote_start(u64 handle)
 	/* Can only happen when in_task(). */
 	if (!area) {
 		local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
-		area = vmalloc(size * sizeof(unsigned long));
+		area = vmalloc_array(size, sizeof(unsigned long));
 		if (!area) {
 			kcov_put(kcov);
 			return;