kselftest: arm64: fake_sigreturn_bad_size_for_magic0

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.

Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

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 (file)
index 0000000..a44b88b
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size_for_magic0.c
@@ -0,0 +1,46 @@
+// 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)
+{
+       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;
+
+       /* at least HDR_SZ for the badly sized terminator. */
+       head = get_starting_head(shead, HDR_SZ, GET_SF_RESV_SIZE(sf), NULL);
+       if (!head)
+               return 0;
+
+       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,
+};