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@xxxxxxx>
---
.../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
