On Thu, Jun 13, 2019 at 12:13:32PM +0100, Cristian Marussi wrote:
Added a simple fake_sigreturn testcase which builds a ucontext_t with a bad magic header and place it onto the stack. Expects a SIGSEGV on test PASS.
Signed-off-by: Cristian Marussi cristian.marussi@arm.com
.../arm64/signal/testcases/.gitignore | 1 + .../testcases/fake_sigreturn_bad_magic.c | 42 +++++++++++++++++++ 2 files changed, 43 insertions(+) create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c
diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore index 3e6b26be6727..c353b7bd899d 100644 --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore @@ -7,3 +7,4 @@ mangle_pstate_invalid_mode_el2 mangle_pstate_invalid_mode_el3 mangle_pstate_ssbs_regs fake_sigreturn_misaligned +fake_sigreturn_bad_magic diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c new file mode 100644 index 000000000000..de81ea10393f --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c @@ -0,0 +1,42 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */
+#include <asm/sigcontext.h> +#include <ucontext.h> +#include <stdio.h>
+#include "test_signals_utils.h" +#include "testcases.h"
+struct a_sigframe sf;
+static int fake_sigreturn_bad_magic_run(struct tdescr *td,
siginfo_t *si, ucontext_t *uc)+{
- struct _aarch64_ctx *head = GET_SF_RESV_HEAD(sf);
- /* just to fill the ucontext_t with something real */
- if (!get_current_context(td, &sf.uc))
return 1;- /* find the terminator, preserving existig headers */
- head = get_terminator(head, GET_SF_RESV_SIZE(sf), NULL);
- if (head) {
head->magic = 0xdeadbeef;head->size = 128;
How can we be sure this won't overrun the end of the sigframe, once the new terminator is appended?
If there is extra_context in the frame, the frame is only as large as needed, so adding another record will always overrun the size of the frame in that case.
I suggest splitting this test into a few cases, something like the following.
(Note, some of these are already covered by your tests. I'm just trying to give the broad view here.)
1) Add a bogus record that doesn't overrun the frame.
2) Add a bogus record that does overrun the frame.
3) Add a record with a bogus size (i.e., not a multiple of 16 bytes, or smaller than _aarch64_ctx).
3) Hack the size field of an existing record so that it overruns the frame. Thee are two subcases here: a record big enough that the next _aarch64_ctx doesn't fit (probably already tested by fake_sigreturn_overflow_reserved), and a record that overruns the frame all by itself (tested by fake_sigreturn_bad_size, but it would be good to check the exact boundary condition -- see my comments on that patch).
When checking that the kernel rejects an _aarch64_ctx header that overruns the end of the frame, we should nonetheless write data for it that looks valid, so that we know the kernel is rejecting it because of the overrun and not because the header contents are invalid.
4) Delete a required record from the frame (say, fpsimd_context). Or just delete everything.
For this series, maybe just do (1): this test nearly does that.
If there is extra_context, we can delete it and replace it with our bogus record: this can't overrun if the bogus record's size is no bigger than extra_context.
We should have tests to cover the other cases, but they can be TODO for now.
[...]
Cheers ---Dave