On Mon, Sep 02, 2019 at 12:29:31pm +0100, Cristian Marussi wrote:
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@arm.com
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);
Nit: can we write this sum the other way round (see comment on patch 9)?
- 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;
Can we also have versions of this test that try:
a) a size that doesn't overflow __reserved[], but is not a multiple of 16 b) a size that is less than 16 c) a size that does overflow __reserved[], but by less than 16 bytes?
These tests are all closely related and can probably be macro-ised easily. They can go on the TODO list for now anyway: let's get this series settled in its current form first.
In any case:
Reviewed-by: Dave Martin Dave.Martin@arm.com