lkml.org 
[lkml]   [2018]   [Jul]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH v6 10/18] x86/power/64: Remove VLA usage
    On Tue, Jul 24, 2018 at 6:49 PM, Kees Cook <keescook@chromium.org> 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>

    I think I can queue this up if there are no objections from others.

    Do you want me to do that?

    > ---
    > arch/x86/power/hibernate_64.c | 36 ++++++++++++++++++++---------------
    > 1 file changed, 21 insertions(+), 15 deletions(-)
    >
    > diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
    > index 67ccf64c8bd8..f8e3b668d20b 100644
    > --- a/arch/x86/power/hibernate_64.c
    > +++ b/arch/x86/power/hibernate_64.c
    > @@ -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;
    > }
    >
    > --
    > 2.17.1
    >

    \
     
     \ /
      Last update: 2018-07-25 13:33    [W:4.155 / U:0.728 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site