Re: [PATCH 2/3] pstore: Improve a size determination in three functions

Kees Cook
2017-08-16T19:33:54Z

On Wed, Aug 16, 2017 at 12:22 PM, SF Markus Elfring
<elfring@users.sourceforge.net> wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Wed, 16 Aug 2017 20:50:15 +0200
>
> Replace the specification of data types by pointer dereferences
> as the parameter for the operator "sizeof" to make the corresponding size
> determination a bit safer according to the Linux coding style convention.

Agreed; this is a robustness change in that changes to the variable
structure will be correctly flowed through to the allocations.

>
> This issue was detected by using the Coccinelle software.

Which script detected this?

-Kees

>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
> fs/pstore/ram.c | 3 +--
> fs/pstore/ram_core.c | 4 ++--
> 2 files changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index 42d27e5fac9f..0ef95c384bed 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -293,8 +293,7 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record)
> */
> struct persistent_ram_zone *tmp_prz, *prz_next;
>
> - tmp_prz = kzalloc(sizeof(struct persistent_ram_zone),
> - GFP_KERNEL);
> + tmp_prz = kzalloc(sizeof(*tmp_prz), GFP_KERNEL);
> if (!tmp_prz)
> return -ENOMEM;
> free_prz = true;
> diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
> index fafa8af1289c..5d9f7280d757 100644
> --- a/fs/pstore/ram_core.c
> +++ b/fs/pstore/ram_core.c
> @@ -405,7 +405,7 @@ static void *persistent_ram_vmap(phys_addr_t start, size_t size,
> else
> prot = pgprot_writecombine(PAGE_KERNEL);
>
> - pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
> + pages = kmalloc_array(page_count, sizeof(*pages), GFP_KERNEL);
> if (!pages)
> return NULL;
>
> @@ -520,7 +520,7 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
> struct persistent_ram_zone *prz;
> int ret = -ENOMEM;
>
> - prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
> + prz = kzalloc(sizeof(*prz), GFP_KERNEL);
> if (!prz)
> goto err;
>
> --
> 2.14.0
>

--
Kees Cook
Pixel Security