* [PATCH] x86/power/64: Remove VLA usage
@ 2018-07-16 3:56 Kees Cook
2018-07-16 8:52 ` Pavel Machek
2018-07-16 17:22 ` Eric Biggers
0 siblings, 2 replies; 4+ messages in thread
From: Kees Cook @ 2018-07-16 3:56 UTC (permalink / raw)
To: Rafael J. Wysocki
Cc: Pavel Machek, Herbert Xu, Arnd Bergmann, Eric Biggers,
Gustavo A. R. Silva, linux-pm, linux-kernel
In the quest to remove all stack VLA usage from the kernel[1], this
removes the discouraged use of AHASH_REQUEST_ON_STACK by switching to
shash directly and allocating the descriptor in heap memory (which should
be fine: the tfm has already been allocated there too).
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/x86/power/hibernate_64.c | 35 +++++++++++++++++++----------------
1 file changed, 19 insertions(+), 16 deletions(-)
diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
index 67ccf64c8bd8..0ed01bb935a6 100644
--- a/arch/x86/power/hibernate_64.c
+++ b/arch/x86/power/hibernate_64.c
@@ -233,28 +233,31 @@ struct restore_data_record {
*/
static int get_e820_md5(struct e820_table *table, void *buf)
{
- struct scatterlist sg;
- struct crypto_ahash *tfm;
+ struct crypto_shash *tfm;
+ struct shash_desc *desc;
int size;
int ret = 0;
- tfm = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
+ tfm = crypto_alloc_shash("md5", 0, 0);
if (IS_ERR(tfm))
return -ENOMEM;
- {
- AHASH_REQUEST_ON_STACK(req, tfm);
- size = offsetof(struct e820_table, entries) + sizeof(struct e820_entry) * table->nr_entries;
- ahash_request_set_tfm(req, tfm);
- sg_init_one(&sg, (u8 *)table, size);
- ahash_request_set_callback(req, 0, NULL, NULL);
- ahash_request_set_crypt(req, &sg, buf, size);
-
- if (crypto_ahash_digest(req))
- ret = -EINVAL;
- ahash_request_zero(req);
- }
- crypto_free_ahash(tfm);
+ desc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
+ GFP_KERNEL);
+ if (!desc)
+ return -ENOMEM;
+
+ desc->tfm = tfm;
+ desc->flags = 0;
+
+ size = offsetof(struct e820_table, entries) +
+ sizeof(struct e820_entry) * table->nr_entries;
+
+ if (crypto_shash_digest(desc, (u8 *)table, size, buf))
+ ret = -EINVAL;
+
+ kzfree(desc);
+ crypto_free_shash(tfm);
return ret;
}
--
2.17.1
--
Kees Cook
Pixel Security
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] x86/power/64: Remove VLA usage
2018-07-16 3:56 [PATCH] x86/power/64: Remove VLA usage Kees Cook
@ 2018-07-16 8:52 ` Pavel Machek
2018-07-16 17:22 ` Eric Biggers
1 sibling, 0 replies; 4+ messages in thread
From: Pavel Machek @ 2018-07-16 8:52 UTC (permalink / raw)
To: Kees Cook
Cc: Rafael J. Wysocki, Herbert Xu, Arnd Bergmann, Eric Biggers,
Gustavo A. R. Silva, linux-pm, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 724 bytes --]
On Sun 2018-07-15 20:56:57, Kees Cook wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> removes the discouraged use of AHASH_REQUEST_ON_STACK by switching to
> shash directly and allocating the descriptor in heap memory (which should
> be fine: the tfm has already been allocated there too).
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
, provided it was tested.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/power/64: Remove VLA usage
2018-07-16 3:56 [PATCH] x86/power/64: Remove VLA usage Kees Cook
2018-07-16 8:52 ` Pavel Machek
@ 2018-07-16 17:22 ` Eric Biggers
2018-07-19 4:39 ` Kees Cook
1 sibling, 1 reply; 4+ messages in thread
From: Eric Biggers @ 2018-07-16 17:22 UTC (permalink / raw)
To: Kees Cook
Cc: Rafael J. Wysocki, Pavel Machek, Herbert Xu, Arnd Bergmann,
Gustavo A. R. Silva, linux-pm, linux-kernel
On Sun, Jul 15, 2018 at 08:56:57PM -0700, Kees Cook wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> removes the discouraged use of AHASH_REQUEST_ON_STACK by switching to
> shash directly and allocating the descriptor in heap memory (which should
> be fine: the tfm has already been allocated there too).
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> arch/x86/power/hibernate_64.c | 35 +++++++++++++++++++----------------
> 1 file changed, 19 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
> index 67ccf64c8bd8..0ed01bb935a6 100644
> --- a/arch/x86/power/hibernate_64.c
> +++ b/arch/x86/power/hibernate_64.c
> @@ -233,28 +233,31 @@ struct restore_data_record {
> */
> static int get_e820_md5(struct e820_table *table, void *buf)
> {
> - struct scatterlist sg;
> - struct crypto_ahash *tfm;
> + struct crypto_shash *tfm;
> + struct shash_desc *desc;
> int size;
> int ret = 0;
>
> - tfm = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
> + tfm = crypto_alloc_shash("md5", 0, 0);
> if (IS_ERR(tfm))
> return -ENOMEM;
>
> - {
> - AHASH_REQUEST_ON_STACK(req, tfm);
> - size = offsetof(struct e820_table, entries) + sizeof(struct e820_entry) * table->nr_entries;
> - ahash_request_set_tfm(req, tfm);
> - sg_init_one(&sg, (u8 *)table, size);
> - ahash_request_set_callback(req, 0, NULL, NULL);
> - ahash_request_set_crypt(req, &sg, buf, size);
> -
> - if (crypto_ahash_digest(req))
> - ret = -EINVAL;
> - ahash_request_zero(req);
> - }
> - crypto_free_ahash(tfm);
> + desc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
> + GFP_KERNEL);
> + if (!desc)
> + return -ENOMEM;
Need crypto_free_shash(tfm) if the kmalloc() here fails.
> +
> + desc->tfm = tfm;
> + desc->flags = 0;
> +
> + size = offsetof(struct e820_table, entries) +
> + sizeof(struct e820_entry) * table->nr_entries;
> +
> + if (crypto_shash_digest(desc, (u8 *)table, size, buf))
> + ret = -EINVAL;
> +
> + kzfree(desc);
> + crypto_free_shash(tfm);
>
> return ret;
> }
> --
> 2.17.1
>
>
> --
> Kees Cook
> Pixel Security
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] x86/power/64: Remove VLA usage
2018-07-16 17:22 ` Eric Biggers
@ 2018-07-19 4:39 ` Kees Cook
0 siblings, 0 replies; 4+ messages in thread
From: Kees Cook @ 2018-07-19 4:39 UTC (permalink / raw)
To: Eric Biggers
Cc: Rafael J. Wysocki, Pavel Machek, Herbert Xu, Arnd Bergmann,
Gustavo A. R. Silva, Linux PM list, LKML
On Mon, Jul 16, 2018 at 10:22 AM, Eric Biggers <ebiggers@google.com> wrote:
> On Sun, Jul 15, 2018 at 08:56:57PM -0700, Kees Cook wrote:
>> In the quest to remove all stack VLA usage from the kernel[1], this
>> removes the discouraged use of AHASH_REQUEST_ON_STACK by switching to
>> shash directly and allocating the descriptor in heap memory (which should
>> be fine: the tfm has already been allocated there too).
>>
>> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>> ---
>> arch/x86/power/hibernate_64.c | 35 +++++++++++++++++++----------------
>> 1 file changed, 19 insertions(+), 16 deletions(-)
>>
>> diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
>> index 67ccf64c8bd8..0ed01bb935a6 100644
>> --- a/arch/x86/power/hibernate_64.c
>> +++ b/arch/x86/power/hibernate_64.c
>> @@ -233,28 +233,31 @@ struct restore_data_record {
>> */
>> static int get_e820_md5(struct e820_table *table, void *buf)
>> {
>> - struct scatterlist sg;
>> - struct crypto_ahash *tfm;
>> + struct crypto_shash *tfm;
>> + struct shash_desc *desc;
>> int size;
>> int ret = 0;
>>
>> - tfm = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
>> + tfm = crypto_alloc_shash("md5", 0, 0);
>> if (IS_ERR(tfm))
>> return -ENOMEM;
>>
>> - {
>> - AHASH_REQUEST_ON_STACK(req, tfm);
>> - size = offsetof(struct e820_table, entries) + sizeof(struct e820_entry) * table->nr_entries;
>> - ahash_request_set_tfm(req, tfm);
>> - sg_init_one(&sg, (u8 *)table, size);
>> - ahash_request_set_callback(req, 0, NULL, NULL);
>> - ahash_request_set_crypt(req, &sg, buf, size);
>> -
>> - if (crypto_ahash_digest(req))
>> - ret = -EINVAL;
>> - ahash_request_zero(req);
>> - }
>> - crypto_free_ahash(tfm);
>> + desc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
>> + GFP_KERNEL);
>> + if (!desc)
>> + return -ENOMEM;
>
> Need crypto_free_shash(tfm) if the kmalloc() here fails.
Ah thanks! Fixed now for the next version.
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-07-19 4:39 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2018-07-16 3:56 [PATCH] x86/power/64: Remove VLA usage Kees Cook
2018-07-16 8:52 ` Pavel Machek
2018-07-16 17:22 ` Eric Biggers
2018-07-19 4:39 ` Kees Cook
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