Add 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@xxxxxxx>
---
v3 --> v4
- fix commit
- missing include
- using new get_starting_head() helper
- added test description
---
.../testcases/fake_sigreturn_bad_size.c | 77 +++++++++++++++++++
1 file changed, 77 insertions(+)
create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c
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..b1156afdb691
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c
@@ -0,0 +1,77 @@
+// 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))
+ return 1;
+
+ resv_sz = GET_SF_RESV_SIZE(sf);
+ /* at least HDR_SZ + bad sized esr_context needed */
+ need_sz = HDR_SZ + sizeof(struct esr_context);
+ head = get_starting_head(shead, need_sz, resv_sz, &offset);
+ if (head) {
+ /*
+ * 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,
+};
--
2.17.1
