Re: [PATCH v5 07/11] kselftest: arm64: fake_sigreturn_bad_size_for_magic0

From: Cristian Marussi <cristian.marussi@arm.com>
To: Dave Martin <Dave.Martin@arm.com>
Cc: linux-kselftest@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, shuah@kernel.org,
	amit.kachhap@arm.com, andreyknvl@google.com
Subject: Re: [PATCH v5 07/11] kselftest: arm64: fake_sigreturn_bad_size_for_magic0
Date: Mon, 9 Sep 2019 18:47:41 +0100	[thread overview]
Message-ID: <5d6c52f8-d689-0665-85fa-367e1e4a148d@arm.com> (raw)
In-Reply-To: <20190904114901.GX27757@arm.com>

On 04/09/2019 12:49, Dave Martin wrote:
> On Mon, Sep 02, 2019 at 12:29:28pm +0100, Cristian Marussi wrote:
>> Add a simple fake_sigreturn testcase which builds a ucontext_t with a
>> badly sized terminator record and place it onto the stack.
>> Expects a SIGSEGV on test PASS.
>>
>> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
>> ---
>> v3 --> v4
>> - fix commit
>> - add signal.h include
>> - using new get_starting_head() helper
>> - added test description
>> ---
>>  .../fake_sigreturn_bad_size_for_magic0.c      | 49 +++++++++++++++++++
>>  1 file changed, 49 insertions(+)
>>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size_for_magic0.c
>>
>> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size_for_magic0.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size_for_magic0.c
>> new file mode 100644
>> index 000000000000..25017fe18214
>> --- /dev/null
>> +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size_for_magic0.c
>> @@ -0,0 +1,49 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2019 ARM Limited
>> + *
>> + * Place a fake sigframe on the stack including a badly sized terminator
>> + * record: on sigreturn Kernel must spot this attempt and the test case
>> + * is expected to be terminated via SEGV.
>> + */
>> +
>> +#include <signal.h>
>> +#include <ucontext.h>
>> +
>> +#include "test_signals_utils.h"
>> +#include "testcases.h"
>> +
>> +struct fake_sigframe sf;
>> +
>> +static int fake_sigreturn_bad_size_for_magic0_run(struct tdescr *td,
>> +						  siginfo_t *si, ucontext_t *uc)
>> +{
>> +	size_t resv_sz, need_sz;
>> +	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);
>> +	/* at least HDR_SZ for the badly sized terminator. */
>> +	need_sz = HDR_SZ;
> 
> Nit: do we need the resv_sz and need_sz variables here?
> 

No

>> +	head = get_starting_head(shead, need_sz, resv_sz, NULL);
>> +	if (head) {
> 
> Perhaps we could fail immediately rather than relying on timeout here?
> 
> Probably not a huge deal though.

Yes I'll do. (I'll review slightly the exit/termination strategy in main()
but it won't be a problem)

> 
>> +		head->magic = 0;
>> +		head->size = HDR_SZ;
>> +
>> +		ASSERT_BAD_CONTEXT(&sf.uc);
>> +		fake_sigreturn(&sf, sizeof(sf), 0);
>> +	}
>> +
>> +	return 1;
>> +}
>> +
>> +struct tdescr tde = {
>> +		.name = "FAKE_SIGRETURN_BAD_SIZE_FOR_TERMINATOR",
>> +		.descr = "Trigger a sigreturn using non-zero size terminator",
>> +		.sig_ok = SIGSEGV,
>> +		.timeout = 3,
>> +		.run = fake_sigreturn_bad_size_for_magic0_run,
>> +};
> 
> Either way,
> 
> Reviewed-by: Dave Martin <Dave.Martin@arm.com>
> 

Thanks

Cheers

Cristian