From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Date: Wed, 25 Jul 2018 11:32:23 +0000 Subject: Re: [PATCH v6 10/18] x86/power/64: Remove VLA usage Message-Id: List-Id: References: <20180724164936.37477-1-keescook@chromium.org> <20180724164936.37477-11-keescook@chromium.org> In-Reply-To: <20180724164936.37477-11-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Kees Cook Cc: Herbert Xu , Arnd Bergmann , Eric Biggers , "Gustavo A. R. Silva" , Alasdair Kergon , Rabin Vincent , Tim Chen , "Rafael J. Wysocki" , Pavel Machek , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , the arch/x86 maintainers , Philipp Reisner , Lars Ellenberg , Jens Axboe , Giovanni Cabiddu , Mike Snitzer , Paul Mackerras , Greg Kroah-Hartman , David Howells , Johannes Berg , Tudor-Dan Ambarus , Jia-Ju Bai , Andrew Morton , Geert Uytterhoeven , Josh Poimboeuf , David Woodhouse , Will Deacon , dm-devel@redhat.com, Linux PM , linux-crypto@vger.kernel.org, drbd-dev@lists.linbit.com, linux-block@vger.kernel.org, qat-linux@intel.com, linux-ppp@vger.kernel.org, netdev , devel@driverdev.osuosl.org, linux-afs@lists.infradead.org, "open list:NETWORKING DRIVERS (WIRELESS)" , Linux Kernel Mailing List On Tue, Jul 24, 2018 at 6:49 PM, 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 > Acked-by: Pavel Machek 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 >