2020-06-15 22:38:06

by Gustavo A. R. Silva

Subject: [PATCH] cifs: misc: Use array_size() in if-statement controlling expression

Use array_size() instead of the open-coded version in the controlling
expression of the if statement.

Also, while there, use the preferred form for passing a size of a struct.
The alternative form where struct name is spelled out hurts readability
and introduces an opportunity for a bug when the pointer variable type is
changed but the corresponding sizeof that is passed as argument is not.

This issue was found with the help of Coccinelle and, audited and fixed
manually.

Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
fs/cifs/misc.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 56791a692c8b..e44d049142d0 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -844,28 +844,26 @@ setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
struct bio_vec *bv = NULL;

if (iov_iter_is_kvec(iter)) {
- memcpy(&ctx->iter, iter, sizeof(struct iov_iter));
+ memcpy(&ctx->iter, iter, sizeof(*iter));
ctx->len = count;
iov_iter_advance(iter, count);
return 0;
}

- if (max_pages * sizeof(struct bio_vec) <= CIFS_AIO_KMALLOC_LIMIT)
- bv = kmalloc_array(max_pages, sizeof(struct bio_vec),
- GFP_KERNEL);
+ if (array_size(max_pages, sizeof(*bv)) <= CIFS_AIO_KMALLOC_LIMIT)
+ bv = kmalloc_array(max_pages, sizeof(*bv), GFP_KERNEL);

if (!bv) {
- bv = vmalloc(array_size(max_pages, sizeof(struct bio_vec)));
+ bv = vmalloc(array_size(max_pages, sizeof(*bv)));
if (!bv)
return -ENOMEM;
}

- if (max_pages * sizeof(struct page *) <= CIFS_AIO_KMALLOC_LIMIT)
- pages = kmalloc_array(max_pages, sizeof(struct page *),
- GFP_KERNEL);
+ if (array_size(max_pages, sizeof(*pages)) <= CIFS_AIO_KMALLOC_LIMIT)
+ pages = kmalloc_array(max_pages, sizeof(*pages), GFP_KERNEL);

if (!pages) {
- pages = vmalloc(array_size(max_pages, sizeof(struct page *)));
+ pages = vmalloc(array_size(max_pages, sizeof(*pages)));
if (!pages) {
kvfree(bv);
return -ENOMEM;
--
2.27.0

2020-06-16 11:21:29

by Aurélien Aptel

Subject: Re: [PATCH] cifs: misc: Use array_size() in if-statement controlling expression

Reviewed-by: Aurelien Aptel <[email protected]>

Cheers,
--
Aurélien Aptel / SUSE Labs Samba Team
GPG: 1839 CB5F 9F5B FB9B AA97 8C99 03C8 A49B 521B D5D3
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)

2020-06-16 18:46:02

by Kees Cook

Subject: Re: [PATCH] cifs: misc: Use array_size() in if-statement controlling expression

On Mon, Jun 15, 2020 at 05:41:12PM -0500, Gustavo A. R. Silva wrote:
> Use array_size() instead of the open-coded version in the controlling
> expression of the if statement.
>
> Also, while there, use the preferred form for passing a size of a struct.
> The alternative form where struct name is spelled out hurts readability
> and introduces an opportunity for a bug when the pointer variable type is
> changed but the corresponding sizeof that is passed as argument is not.
>
> This issue was found with the help of Coccinelle and, audited and fixed
> manually.
>
> Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83
> Signed-off-by: Gustavo A. R. Silva <[email protected]>

Reviewed-by: Kees Cook <[email protected]>

--
Kees Cook

2020-06-16 19:42:26

by Steve French

Subject: Re: [PATCH] cifs: misc: Use array_size() in if-statement controlling expression

Added the two reviewed-bys and merged into cifs-2.6.git for-next

On Tue, Jun 16, 2020 at 6:17 AM Aurélien Aptel via samba-technical
<[email protected]> wrote:
>
> Reviewed-by: Aurelien Aptel <[email protected]>
>
> Cheers,
> --
> Aurélien Aptel / SUSE Labs Samba Team
> GPG: 1839 CB5F 9F5B FB9B AA97 8C99 03C8 A49B 521B D5D3
> SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)
>


--
Thanks,

Steve