From: Cristian Marussi <cristian.marussi@arm.com>
To: Dave Martin <Dave.Martin@arm.com>
Cc: andreyknvl@google.com, shuah@kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 10/11] kselftest: arm64: fake_sigreturn_bad_size
Date: Fri, 30 Aug 2019 16:21:29 +0100 [thread overview]
Message-ID: <599bc78e-718d-0475-0ab0-79e1277e55ab@arm.com> (raw)
In-Reply-To: <20190813162646.GH10425@arm.com>
On 13/08/2019 17:26, Dave Martin wrote:
> On Fri, Aug 02, 2019 at 06:02:59PM +0100, Cristian Marussi wrote:
>> Added a simple fake_sigreturn testcase which builds a ucontext_t
>
> Add
Ok
>
>> with a badly sized header that causes a overrun in the __reserved
>> area and place it onto the stack. Expects a SIGSEGV on test PASS.
>>
>> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
>> ---
>> .../arm64/signal/testcases/.gitignore | 1 +
>> .../testcases/fake_sigreturn_bad_size.c | 85 +++++++++++++++++++
>> 2 files changed, 86 insertions(+)
>> create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c
>>
>> diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore
>> index 94f9baaf638c..3408e0f5ba98 100644
>> --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore
>> +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore
>> @@ -8,3 +8,4 @@ fake_sigreturn_bad_magic
>> fake_sigreturn_bad_size_for_magic0
>> fake_sigreturn_missing_fpsimd
>> fake_sigreturn_duplicated_fpsimd
>> +fake_sigreturn_bad_size
>> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c
>> new file mode 100644
>> index 000000000000..1467fb534d8b
>> --- /dev/null
>> +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c
>> @@ -0,0 +1,85 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/* Copyright (C) 2019 ARM Limited */
>> +
>
> signal.h?
>
Ok
>> +#include <stdio.h>
>> +#include <ucontext.h>
>> +
>> +#include "test_signals_utils.h"
>> +#include "testcases.h"
>> +
>> +struct fake_sigframe sf;
>> +
>> +#define MIN_SZ_ALIGN 16
>> +
>> +static int fake_sigreturn_bad_size_run(struct tdescr *td,
>> + siginfo_t *si, ucontext_t *uc)
>> +{
>> + size_t resv_sz, need_sz, offset;
>> + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head;
>> +
>> + /* just to fill the ucontext_t with something real */
>> + if (!get_current_context(td, &sf.uc))
>> + return 1;
>> +
>> + resv_sz = GET_SF_RESV_SIZE(sf);
>> + /*
>> + * find the terminator, preserving existing headers
>> + * and verify amount of spare room in __reserved area.
>> + */
>> + head = get_terminator(shead, resv_sz, &offset);
>> + /*
>> + * try stripping extra_context header when low on space:
>> + * we need at least for the bad sized esr_context.
>
> double space
>
ok.
>> + */
>> + need_sz = HDR_SZ + sizeof(struct esr_context);
>> + if (head && resv_sz - offset < need_sz) {
>> + fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n",
>> + resv_sz - offset);
>> + head = get_header(shead, EXTRA_MAGIC, resv_sz, &offset);
>> + }
>> + /* just give up and timeout if still not enough space */
>> + if (head && resv_sz - offset >= need_sz) {
>> + fprintf(stderr, "Mangling template header. Spare space:%zd\n",
>> + resv_sz - offset);
>> + /*
>> + * Use an esr_context to build a fake header with a
>> + * size greater then the free __reserved area minus HDR_SZ;
>> + * using ESR_MAGIC here since it is not checked for size nor
>> + * is limited to one instance.
>> + *
>> + * At first inject an additional normal esr_context
>> + */
>> + head->magic = ESR_MAGIC;
>> + head->size = sizeof(struct esr_context);
>> + /* and terminate properly */
>> + write_terminator_record(GET_RESV_NEXT_HEAD(head));
>> + ASSERT_GOOD_CONTEXT(&sf.uc);
>> +
>> + /*
>> + * now mess with fake esr_context size: leaving less space than
>> + * neededwhile keeping size value 16-aligned
>> + *
>> + * It must trigger a SEGV from Kernel on:
>> + *
>> + * resv_sz - offset < sizeof(*head)
>> + */
>> + /* at first set the maximum good 16-aligned size */
>> + head->size = (resv_sz - offset - need_sz + MIN_SZ_ALIGN) & ~0xfUL;
>> + /* plus a bit more of 16-aligned sized stuff */
>> + head->size += MIN_SZ_ALIGN;
>> + /* and terminate properly */
>> + write_terminator_record(GET_RESV_NEXT_HEAD(head));
>> + ASSERT_BAD_CONTEXT(&sf.uc);
>> + fake_sigreturn(&sf, sizeof(sf), 16);
>> + }
>> +
>> + return 1;
>> +}
>
I'll convert to use new helper get_starting_head() to make space in __reserved.
> [...]
>
> Otherwise looks reasonable.
>
> Cheers
> ---Dave
Cheers
Cristian
>
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next prev parent reply other threads:[~2019-08-30 15:21 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 17:02 [PATCH v3 00/11] Add arm64/signal initial kselftest support Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 01/11] kselftest: arm64: introduce new boilerplate code Cristian Marussi
2019-08-13 16:23 ` Dave Martin
2019-08-27 12:14 ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 02/11] kselftest: arm64: adds first test and common utils Cristian Marussi
2019-08-06 15:50 ` Cristian Marussi
2019-08-07 15:42 ` Cristian Marussi
2019-08-09 10:54 ` Cristian Marussi
2019-08-09 11:16 ` Dave Martin
2019-08-09 12:20 ` Cristian Marussi
2019-08-09 12:32 ` Dave Martin
2019-08-12 12:43 ` Amit Kachhap
2019-08-13 13:22 ` Cristian Marussi
2019-08-14 10:22 ` Amit Kachhap
2019-08-27 14:24 ` Cristian Marussi
2019-08-13 16:24 ` Dave Martin
2019-08-28 17:34 ` Cristian Marussi
2019-09-03 15:34 ` Dave Martin
2019-09-03 16:08 ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 03/11] kselftest: arm64: mangle_pstate_invalid_daif_bits Cristian Marussi
2019-08-13 16:24 ` Dave Martin
2019-08-29 10:19 ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 04/11] kselftest: arm64: mangle_pstate_invalid_mode_el Cristian Marussi
2019-08-13 16:24 ` Dave Martin
2019-08-29 11:50 ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 05/11] kselftest: arm64: mangle_pstate_ssbs_regs Cristian Marussi
2019-08-13 16:25 ` Dave Martin
2019-08-29 15:35 ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 06/11] kselftest: arm64: fake_sigreturn_bad_magic Cristian Marussi
2019-08-13 16:25 ` Dave Martin
2019-08-30 14:29 ` Cristian Marussi
2019-09-04 10:05 ` Dave Martin
2019-09-04 10:37 ` Cristian Marussi
2019-09-04 10:47 ` Dave Martin
2019-08-02 17:02 ` [PATCH v3 07/11] kselftest: arm64: fake_sigreturn_bad_size_for_magic0 Cristian Marussi
2019-08-13 16:25 ` Dave Martin
2019-08-30 14:49 ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 08/11] kselftest: arm64: fake_sigreturn_missing_fpsimd Cristian Marussi
2019-08-13 16:26 ` Dave Martin
2019-08-30 14:55 ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 09/11] kselftest: arm64: fake_sigreturn_duplicated_fpsimd Cristian Marussi
2019-08-13 16:26 ` Dave Martin
2019-08-30 15:11 ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 10/11] kselftest: arm64: fake_sigreturn_bad_size Cristian Marussi
2019-08-13 16:26 ` Dave Martin
2019-08-30 15:21 ` Cristian Marussi [this message]
2019-08-02 17:03 ` [PATCH v3 11/11] kselftest: arm64: fake_sigreturn_misaligned_sp Cristian Marussi
2019-08-07 16:04 ` Cristian Marussi
2019-08-13 16:28 ` Dave Martin
2019-08-30 15:22 ` Cristian Marussi
2019-08-13 16:27 ` Dave Martin
2019-08-30 16:33 ` Cristian Marussi
2019-08-13 16:22 ` [PATCH v3 00/11] Add arm64/signal initial kselftest support Dave Martin
2019-08-30 16:40 ` Cristian Marussi
2019-09-02 10:53 ` Dave Martin
2019-09-02 11:30 ` Cristian Marussi
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