From: Dave Martin <Dave.Martin@arm.com> To: Cristian Marussi <cristian.marussi@arm.com> Cc: linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org, shuah@kernel.org, andreyknvl@google.com Subject: Re: [PATCH v3 06/11] kselftest: arm64: fake_sigreturn_bad_magic Date: Tue, 13 Aug 2019 17:25:23 +0100 Message-ID: <20190813162523.GD10425@arm.com> (raw) In-Reply-To: <20190802170300.20662-7-cristian.marussi@arm.com> On Fri, Aug 02, 2019 at 06:02:55PM +0100, Cristian Marussi wrote: > Added a simple fake_sigreturn testcase which builds a ucontext_t Add > with a bad magic header and place it onto the stack. > Expects a SIGSEGV on test PASS. > This commit also introduces a common utility assembly function to > invoke a sigreturn using a fake provided sigframe. > > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> > --- > tools/testing/selftests/arm64/signal/Makefile | 2 +- > .../testing/selftests/arm64/signal/signals.S | 64 +++++++++++++++++++ > .../arm64/signal/test_signals_utils.h | 1 + > .../arm64/signal/testcases/.gitignore | 1 + > .../testcases/fake_sigreturn_bad_magic.c | 63 ++++++++++++++++++ > 5 files changed, 130 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/arm64/signal/signals.S > create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c > > diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile > index 8c8d08be4b0d..b3dcf315b5a4 100644 > --- a/tools/testing/selftests/arm64/signal/Makefile > +++ b/tools/testing/selftests/arm64/signal/Makefile > @@ -80,7 +80,7 @@ endif > # Common test-unit targets to build common-layout test-cases executables > # Needs secondary expansion to properly include the testcase c-file in pre-reqs > .SECONDEXPANSION: > -$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h > +$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c signals.S $$@.c test_signals.h test_signals_utils.h testcases/testcases.h > @if [ ! -d $(khdr_dir) ]; then \ > echo -n "\n!!! WARNING: $(khdr_dir) NOT FOUND."; \ > echo "===> Are you sure Kernel Headers have been installed properly ?\n"; \ > diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S > new file mode 100644 > index 000000000000..6262b877400b > --- /dev/null > +++ b/tools/testing/selftests/arm64/signal/signals.S > @@ -0,0 +1,64 @@ > +/* > + * SPDX-License-Identifier: GPL-2.0 > + * Copyright (C) 2019 ARM Limited > + */ > + > +#include <asm/unistd.h> > + > +.section ".rodata", "a" The section name is not usually quoted in .section (though I guess it works). > +call_fmt: > + .asciz "Calling sigreturn with fake sigframe sized:%zd at calculated SP @%08lX\n" > + > +.text > + > +.globl fake_sigreturn > + > +/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:alignment_SP */ > +fake_sigreturn: > + mov x20, x0 > + mov x21, x1 > + mov x22, x2 > + mov x23, sp > + > + /* create space on the stack for fake sigframe..."x22"-aligned */ > + mov x0, #0 Why to we move 0 into x0? We clobber x0 again in the next instruction: > + add x0, x21, x22 > + sub x22, x22, #1 > + bic x0, x0, x22 > + sub x23, x23, x0 Can you explain the logic here? I'm not sure I understand what this is trying to do exactly. I notice you further modify this in patch 11 -- see my comments there, where I also suggest an alternative way of specifying a misaligned frame that might be simpler. > + > + ldr x0, =call_fmt > + mov x1, x21 > + mov x2, x23 > + bl printf > + > + mov sp, x23 > + > + /* now fill it with the provided content... */ > + mov x0, sp > + mov x1, x20 > + mov x2, x21 > + bl memcpy > + > + /* > + * Here saving a last minute SP to current->token acts as a marker: > + * if we got here, we are successfully faking a sigreturn; in other > + * words we are sure no bad fatal signal has been raised till now > + * for unrelated reasons, so we should consider the possibl observed typo: possible (or possibly?) > + * fatal signal like SEGV coming from Kernel restore_sigframe() and > + * triggered as expected from our test-case. > + * For simplicity this assumes that current field 'token' is laid out > + * as first in struct tdescr > + */ > + ldr x0, current > + str x23, [x0] > + /* SP is already pointing back to the just built fake sigframe here */ > + mov x8, #__NR_rt_sigreturn > + svc #0 > + > + /* > + * Above sigreturn should not return...looping here leads to a timeout > + * and ensure proper and clean test failure, instead of jumping around > + * on a potentially corrupted stack. > + */ > + b . > diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h > index ce35be8ebc8e..2a71da7e6695 100644 > --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h > +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h > @@ -12,4 +12,5 @@ int test_run(struct tdescr *td); > void test_result(struct tdescr *td); > > bool get_current_context(struct tdescr *td, ucontext_t *dest_uc); > +int fake_sigreturn(void *sigframe, size_t sz, int alignment); > #endif > diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore > index a48a118b1a1a..0ea6fdc3765c 100644 > --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore > +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore > @@ -4,3 +4,4 @@ mangle_pstate_invalid_mode_el1 > mangle_pstate_invalid_mode_el2 > mangle_pstate_invalid_mode_el3 > mangle_pstate_ssbs_regs > +fake_sigreturn_bad_magic > diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c > new file mode 100644 > index 000000000000..b4c063e02a7a > --- /dev/null > +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c > @@ -0,0 +1,63 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* Copyright (C) 2019 ARM Limited */ > + We should probably also include <signal.h> here, since we're using siginfo_t etc. > +#include <stdio.h> > +#include <ucontext.h> > + > +#include "test_signals_utils.h" > +#include "testcases.h" > + > +struct fake_sigframe sf; > + > +static int fake_sigreturn_bad_magic_run(struct tdescr *td, > + siginfo_t *si, ucontext_t *uc) > +{ > + size_t resv_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 2*HDR_SZ space ... one for the KSFT_BAD_MAGIC > + * and the other for the usual terminator. > + */ > + if (head && resv_sz - offset < HDR_SZ * 2) { Can we factor out this logic for finding space in the signal frame? We do pretty much the same thing in all the fake_sigreturn tests... > + 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 */ Do we actually time out? I don't see where we actually wait, so doesn't test_run() just fail immediately? The same applies to all the other fake_sigreturn tests too. > + if (head && resv_sz - offset >= HDR_SZ) { Should this be HDR_SZ * 2 again? We need space for the face header and space to write a terminator after it. > + fprintf(stderr, "Mangling template header. Spare space:%zd\n", > + resv_sz - offset); > + /* > + * use a well known NON existent bad magic...something > + * we should pretty sure won't be ever defined in Kernel > + */ > + head->magic = KSFT_BAD_MAGIC; > + head->size = HDR_SZ; > + write_terminator_record(GET_RESV_NEXT_HEAD(head)); > + > + ASSERT_BAD_CONTEXT(&sf.uc); > + fake_sigreturn(&sf, sizeof(sf), 16); > + } > + > + return 1; > +} [...] Cheers ---Dave
next prev parent reply index 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 [this message] 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 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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