From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id A462F6B000C for ; Tue, 6 Mar 2018 12:20:09 -0500 (EST) Received: by mail-pf0-f198.google.com with SMTP id j8so10568921pfh.13 for ; Tue, 06 Mar 2018 09:20:09 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id n23-v6sor4885709plp.141.2018.03.06.09.20.08 for (Google Transport Security); Tue, 06 Mar 2018 09:20:08 -0800 (PST) Subject: Re: [PATCH 6/7] lkdtm: crash on overwriting protected pmalloc var References: <20180228200620.30026-1-igor.stoppa@huawei.com> <20180228200620.30026-7-igor.stoppa@huawei.com> From: J Freyensee Message-ID: <1723ee8d-c89e-0704-c2c3-254eda39dc8b@gmail.com> Date: Tue, 6 Mar 2018 09:20:04 -0800 MIME-Version: 1.0 In-Reply-To: <20180228200620.30026-7-igor.stoppa@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: Igor Stoppa , david@fromorbit.com, willy@infradead.org, keescook@chromium.org, mhocko@kernel.org Cc: labbott@redhat.com, linux-security-module@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com On 2/28/18 12:06 PM, Igor Stoppa wrote: > Verify that pmalloc read-only protection is in place: trying to > overwrite a protected variable will crash the kernel. > > Signed-off-by: Igor Stoppa > --- > drivers/misc/lkdtm.h | 1 + > drivers/misc/lkdtm_core.c | 3 +++ > drivers/misc/lkdtm_perms.c | 28 ++++++++++++++++++++++++++++ > 3 files changed, 32 insertions(+) > > diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h > index 9e513dcfd809..dcda3ae76ceb 100644 > --- a/drivers/misc/lkdtm.h > +++ b/drivers/misc/lkdtm.h > @@ -38,6 +38,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void); > void __init lkdtm_perms_init(void); > void lkdtm_WRITE_RO(void); > void lkdtm_WRITE_RO_AFTER_INIT(void); > +void lkdtm_WRITE_RO_PMALLOC(void); Does this need some sort of #ifdef too? > void lkdtm_WRITE_KERN(void); > void lkdtm_EXEC_DATA(void); > void lkdtm_EXEC_STACK(void); > diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c > index 2154d1bfd18b..c9fd42bda6ee 100644 > --- a/drivers/misc/lkdtm_core.c > +++ b/drivers/misc/lkdtm_core.c > @@ -155,6 +155,9 @@ static const struct crashtype crashtypes[] = { > CRASHTYPE(ACCESS_USERSPACE), > CRASHTYPE(WRITE_RO), > CRASHTYPE(WRITE_RO_AFTER_INIT), > +#ifdef CONFIG_PROTECTABLE_MEMORY > + CRASHTYPE(WRITE_RO_PMALLOC), > +#endif > CRASHTYPE(WRITE_KERN), > CRASHTYPE(REFCOUNT_INC_OVERFLOW), > CRASHTYPE(REFCOUNT_ADD_OVERFLOW), > diff --git a/drivers/misc/lkdtm_perms.c b/drivers/misc/lkdtm_perms.c > index 53b85c9d16b8..0ac9023fd2b0 100644 > --- a/drivers/misc/lkdtm_perms.c > +++ b/drivers/misc/lkdtm_perms.c > @@ -9,6 +9,7 @@ > #include > #include > #include > +#include > #include > > /* Whether or not to fill the target memory area with do_nothing(). */ > @@ -104,6 +105,33 @@ void lkdtm_WRITE_RO_AFTER_INIT(void) > *ptr ^= 0xabcd1234; > } > > +#ifdef CONFIG_PROTECTABLE_MEMORY > +void lkdtm_WRITE_RO_PMALLOC(void) > +{ > + struct gen_pool *pool; > + int *i; > + > + pool = pmalloc_create_pool("pool", 0); > + if (unlikely(!pool)) { > + pr_info("Failed preparing pool for pmalloc test."); > + return; > + } > + > + i = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL); > + if (unlikely(!i)) { > + pr_info("Failed allocating memory for pmalloc test."); > + pmalloc_destroy_pool(pool); > + return; > + } > + > + *i = INT_MAX; > + pmalloc_protect_pool(pool); > + > + pr_info("attempting bad pmalloc write at %p\n", i); > + *i = 0; OK, now I'm on the right version of this patch series, same comment applies.A I don't get the local *i assignment at the end of the function, but seems harmless. Except the two minor comments, otherwise, Reviewed-by: Jay Freyensee > +} > +#endif > + > void lkdtm_WRITE_KERN(void) > { > size_t size; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org