kselftest: arm64: fake_sigreturn_bad_magic (6c2aa428) · Commits · 戴 / test

tools/testing/selftests/arm64/signal/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -28,5 +28,5 @@ clean:
		# 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
		$(CC) $(CFLAGS) $^ -o $@

tools/testing/selftests/arm64/signal/signals.S

0 → 100644

+64 −0

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		/* SPDX-License-Identifier: GPL-2.0 */
		/* Copyright (C) 2019 ARM Limited */

		#include <asm/unistd.h>

		.section .rodata, "a"
		call_fmt:
		.asciz "Calling sigreturn with fake sigframe sized:%zd at SP @%08lX\n"

		.text

		.globl fake_sigreturn

		/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:misalign_bytes */
		fake_sigreturn:
		stp x29, x30, [sp, #-16]!
		mov x29, sp

		mov x20, x0
		mov x21, x1
		mov x22, x2

		/* create space on the stack for fake sigframe 16 bytes-aligned */
		add x0, x21, x22
		add x0, x0, #15
		bic x0, x0, #15 /* round_up(sigframe_size + misalign_bytes, 16) */
		sub sp, sp, x0
		add x23, sp, x22 /* new sigframe base with misaligment if any */

		ldr x0, =call_fmt
		mov x1, x21
		mov x2, x23
		bl printf

		/* memcpy the provided content, while still keeping SP aligned */
		mov x0, x23
		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 possibly observed
		* 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]
		/* finally move SP to misaligned address...if any requested */
		mov sp, x23

		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 .

tools/testing/selftests/arm64/signal/test_signals_utils.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -115,4 +115,6 @@ static __always_inline bool get_current_context(struct tdescr *td,

		return td->live_uc_valid;
		}

		int fake_sigreturn(void *sigframe, size_t sz, int misalign_bytes);
		#endif

tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c

0 → 100644

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		// SPDX-License-Identifier: GPL-2.0
		/*
		* Copyright (C) 2019 ARM Limited
		*
		* Place a fake sigframe on the stack including a BAD Unknown magic
		* 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_magic_run(struct tdescr *td,
		siginfo_t si, ucontext_t uc)
		{
		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;

		/* need at least 2HDR_SZ space: KSFT_BAD_MAGIC + terminator. /
		head = get_starting_head(shead, HDR_SZ * 2, GET_SF_RESV_SIZE(sf), NULL);
		if (!head)
		return 0;

		/*
		* 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), 0);

		return 1;
		}

		struct tdescr tde = {
		.name = "FAKE_SIGRETURN_BAD_MAGIC",
		.descr = "Trigger a sigreturn with a sigframe with a bad magic",
		.sig_ok = SIGSEGV,
		.timeout = 3,
		.run = fake_sigreturn_bad_magic_run,
		};

tools/testing/selftests/arm64/signal/testcases/testcases.c

+46 −0

Original line number	Diff line number	Diff line
		@@ -148,3 +148,49 @@ bool validate_reserved(ucontext_t uc, size_t resv_sz, char *err)

		return true;
		}

		/*
		* This function walks through the records inside the provided reserved area
		* trying to find enough space to fit @need_sz bytes: if not enough space is
		* available and an extra_context record is present, it throws away the
		* extra_context record.
		*
		* It returns a pointer to a new header where it is possible to start storing
		* our need_sz bytes.
		*
		* @shead: points to the start of reserved area
		* @need_sz: needed bytes
		* @resv_sz: reserved area size in bytes
		* @offset: if not null, this will be filled with the offset of the return
		* head pointer from @shead
		*
		* @return: pointer to a new head where to start storing need_sz bytes, or
		* NULL if space could not be made available.
		*/
		struct _aarch64_ctx get_starting_head(struct _aarch64_ctx shead,
		size_t need_sz, size_t resv_sz,
		size_t *offset)
		{
		size_t offs = 0;
		struct _aarch64_ctx *head;

		head = get_terminator(shead, resv_sz, &offs);
		/* not found a terminator...no need to update offset if any */
		if (!head)
		return head;
		if (resv_sz - offs < need_sz) {
		fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n",
		resv_sz - offs);
		head = get_header(shead, EXTRA_MAGIC, resv_sz, &offs);
		if (!head \|\| resv_sz - offs < need_sz) {
		fprintf(stderr,
		"Failed to reclaim space on sigframe.\n");
		return NULL;
		}
		}

		fprintf(stderr, "Available space:%zd\n", resv_sz - offs);
		if (offset)
		*offset = offs;
		return head;
		}

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