Hi
On 6/21/19 11:36 AM, Dave Martin wrote:
On Thu, Jun 13, 2019 at 12:13:33PM +0100, Cristian Marussi wrote:
Added a simple fake_sigreturn testcase which builds a ucontext_t with a badly sized 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_size.c | 40 +++++++++++++++++++ 2 files changed, 41 insertions(+) create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c
diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore index c353b7bd899d..9ad1735e0018 100644 --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore @@ -8,3 +8,4 @@ mangle_pstate_invalid_mode_el3 mangle_pstate_ssbs_regs fake_sigreturn_misaligned fake_sigreturn_bad_magic +fake_sigreturn_bad_size 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..d54f79d63bf6 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */
+#include <asm/sigcontext.h> +#include <ucontext.h>
+#include "test_signals_utils.h" +#include "testcases.h"
+struct a_sigframe sf;
+static int fake_sigreturn_bad_size_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;- /* Tampering size to an unplausible number should cause a SEGV */
- head = get_terminator(head, GET_SF_RESV_SIZE(sf), NULL);
- if (head) {
head->magic = ESR_MAGIC;Add a comment to say why we're using this magic?
head->size = GET_SF_RESV_SIZE(sf) * 2;If we have extra_context, this might not be an invalid size, because extra_context can be much larger than sizeof(__reserved) ... but also we will overrun anyway, because extra_context should already be only just large enough to accommodate the original terminator.
As with the previous test, we should probably throw away the extra_context record (if any) and replace it with this new record.
We should check the actual boundary condition here, rather than just testing with a giant size: we want to make the kernel detects any overrun, however small.
We should also write a valid terminator after the new record, so that we know the kernel is detecting the size overrun instead of rejecting the next record because it is garbage.
Fixed in V2: throwing away the extra when needed, and adding a bogus ESR_MAGIC with a bogus size, large enough to fit all the remaining free __reserved (- NULL terminator space) + 16 bytes (to be still aligned and crashing out on an overrun of the least minimum size) and terminated with another NULL
Cristian
ASSERT_BAD_CONTEXT(&sf.uc);fake_sigreturn(&sf, sizeof(sf), 16);- }
- return 1;
+}
[...]
Cheers ---Dave