// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2019 ARM Limited
 *
 * Place a fake sigframe on the stack including a bad record overflowing
 * the __reserved space: 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;

#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, sizeof(sf.uc)))
                return 1;

        resv_sz = GET_SF_RESV_SIZE(sf);
        /* at least HDR_SZ + bad sized esr_context needed */
        need_sz = sizeof(struct esr_context) + HDR_SZ;
        head = get_starting_head(shead, need_sz, resv_sz, &offset);
        if (!head)
                return 0;

        /*
         * 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
         * needed while 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), 0);

        return 1;
}

struct tdescr tde = {
                .name = "FAKE_SIGRETURN_BAD_SIZE",
                .descr = "Triggers a sigreturn with a overrun __reserved area",
                .sig_ok = SIGSEGV,
                .timeout = 3,
                .run = fake_sigreturn_bad_size_run,
};