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x86/power/hibernate_64: Remove VLA usage 

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).

Link: https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com # [1]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
hifive-unleashed-5.1
Kees Cook 2018-07-24 09:49:28 -07:00 committed by Rafael J. Wysocki
parent d5641c64c4
commit c2cd0b08e1
1 changed files with 21 additions and 15 deletions
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36
arch/x86/power/hibernate_64.c
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@ -233,29 +233,35 @@ 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);
desc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
GFP_KERNEL);
if (!desc) {
ret = -ENOMEM;
goto free_tfm;
}
crypto_free_ahash(tfm);
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);
free_tfm:
crypto_free_shash(tfm);
return ret;
}