On Mon, Jul 16, 2018 at 10:22 AM, Eric Biggers <ebigg...@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=qpxydaacu1rq...@mail.gmail.com >> >> Signed-off-by: Kees Cook <keesc...@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
