[v3,10/11] kselftest: arm64: fake_sigreturn_bad_size
diff mbox series

Message ID 20190802170300.20662-11-cristian.marussi@arm.com
State New
Headers show
Series
  • Add arm64/signal initial kselftest support
Related show

Commit Message

Cristian Marussi Aug. 2, 2019, 5:02 p.m. UTC
Added a simple fake_sigreturn testcase which builds a ucontext_t
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

Comments

Dave Martin Aug. 13, 2019, 4:26 p.m. UTC | #1
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

> 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?

> +#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

> +	 */
> +	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;
> +}

[...]

Otherwise looks reasonable.

Cheers
---Dave
Cristian Marussi Aug. 30, 2019, 3:21 p.m. UTC | #2
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
>

Patch
diff mbox series

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 */
+
+#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.
+	 */
+	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;
+}
+
+struct tdescr tde = {
+		.name = "FAKE_SIGRETURN_BAD_SIZE",
+		.descr = "Triggers a fake sigreturn with a sigframe including a badly sized header which overruns the __reserved area",
+		.sig_ok = SIGSEGV,
+		.timeout = 3,
+		.run = fake_sigreturn_bad_size_run,
+};