On Mon, Oct 07, 2019 at 07:29:49pm +0100, Cristian Marussi wrote:
Add 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.
Introduce a common utility assembly trampoline function to invoke a sigreturn while placing the provided sigframe at wanted alignment and also an helper to make space when needed inside the sigframe reserved area.
Signed-off-by: Cristian Marussi cristian.marussi@arm.com
Looks good to me now:
Reviewed-by: Dave Martin Dave.Martin@arm.com
Cheers ---Dave
v6 --> v7
- fix fake_sigreturn alignment routines (+15)
v5 --> v6
- fake_sigreturn: cleaned up, avoiding excessive SP misalignments
- fake_sigreturn: better formatting and prologue
- get_starting_header: cleand up and commented
- avoid timeout on failure
v3 --> v4
- fix commit
- fix signal.S, handle misalign requests too
- remove unneeded comments
- add signal.h include
- added get_starting_head() helper
- added test description
tools/testing/selftests/arm64/signal/Makefile | 2 +- .../testing/selftests/arm64/signal/signals.S | 64 +++++++++++++++++++ .../arm64/signal/test_signals_utils.h | 2 + .../testcases/fake_sigreturn_bad_magic.c | 52 +++++++++++++++ .../arm64/signal/testcases/testcases.c | 46 +++++++++++++ .../arm64/signal/testcases/testcases.h | 4 ++ 6 files changed, 169 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/arm64/signal/signals.S create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c
diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile index f78f5190e3d4..b497cfea4643 100644 --- a/tools/testing/selftests/arm64/signal/Makefile +++ b/tools/testing/selftests/arm64/signal/Makefile @@ -28,5 +28,5 @@ clean: # Common test-unit targets to build common-layout test-cases executables # Needs secondary expansion to properly include the testcase c-file in pre-reqs .SECONDEXPANSION: -$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h +$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c signals.S $$@.c test_signals.h test_signals_utils.h testcases/testcases.h $(CC) $(CFLAGS) $^ -o $@ diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S new file mode 100644 index 000000000000..9f8c1aefc3b9 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/signals.S @@ -0,0 +1,64 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */
+#include <asm/unistd.h>
+.section .rodata, "a" +call_fmt:
- .asciz "Calling sigreturn with fake sigframe sized:%zd at SP @%08lX\n"
+.text
+.globl fake_sigreturn
+/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:misalign_bytes */ +fake_sigreturn:
- stp x29, x30, [sp, #-16]!
- mov x29, sp
- mov x20, x0
- mov x21, x1
- mov x22, x2
- /* create space on the stack for fake sigframe 16 bytes-aligned */
- add x0, x21, x22
- add x0, x0, #15
- bic x0, x0, #15 /* round_up(sigframe_size + misalign_bytes, 16) */
- sub sp, sp, x0
- add x23, sp, x22 /* new sigframe base with misaligment if any */
- ldr x0, =call_fmt
- mov x1, x21
- mov x2, x23
- bl printf
- /* memcpy the provided content, while still keeping SP aligned */
- mov x0, x23
- mov x1, x20
- mov x2, x21
- bl memcpy
- /*
* Here saving a last minute SP to current->token acts as a marker:* if we got here, we are successfully faking a sigreturn; in other* words we are sure no bad fatal signal has been raised till now* for unrelated reasons, so we should consider the possibly observed* fatal signal like SEGV coming from Kernel restore_sigframe() and* triggered as expected from our test-case.* For simplicity this assumes that current field 'token' is laid out* as first in struct tdescr*/- ldr x0, current
- str x23, [x0]
- /* finally move SP to misaligned address...if any requested */
- mov sp, x23
- mov x8, #__NR_rt_sigreturn
- svc #0
- /*
* Above sigreturn should not return...looping here leads to a timeout* and ensure proper and clean test failure, instead of jumping around* on a potentially corrupted stack.*/- b .
diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h index fd67b1f23c41..6772b5c8d274 100644 --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h @@ -115,4 +115,6 @@ static __always_inline bool get_current_context(struct tdescr *td, return td->live_uc_valid; }
+int fake_sigreturn(void *sigframe, size_t sz, int misalign_bytes); #endif 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..8dc600a7d4fd --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c @@ -0,0 +1,52 @@ +// SPDX-License-Identifier: GPL-2.0 +/*
- Copyright (C) 2019 ARM Limited
- Place a fake sigframe on the stack including a BAD Unknown magic
- record: 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;
+static int fake_sigreturn_bad_magic_run(struct tdescr *td,
siginfo_t *si, ucontext_t *uc)+{
- 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;- /* need at least 2*HDR_SZ space: KSFT_BAD_MAGIC + terminator. */
- head = get_starting_head(shead, HDR_SZ * 2, GET_SF_RESV_SIZE(sf), NULL);
- if (!head)
return 0;- /*
* use a well known NON existent bad magic...something* we should pretty sure won't be ever defined in Kernel*/- head->magic = KSFT_BAD_MAGIC;
- head->size = HDR_SZ;
- 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_MAGIC",.descr = "Trigger a sigreturn with a sigframe with a bad magic",.sig_ok = SIGSEGV,.timeout = 3,.run = fake_sigreturn_bad_magic_run,+}; diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.c b/tools/testing/selftests/arm64/signal/testcases/testcases.c index 1914a01222a1..e3521949b800 100644 --- a/tools/testing/selftests/arm64/signal/testcases/testcases.c +++ b/tools/testing/selftests/arm64/signal/testcases/testcases.c @@ -148,3 +148,49 @@ bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err) return true; }
+/*
- This function walks through the records inside the provided reserved area
- trying to find enough space to fit @need_sz bytes: if not enough space is
- available and an extra_context record is present, it throws away the
- extra_context record.
- It returns a pointer to a new header where it is possible to start storing
- our need_sz bytes.
- @shead: points to the start of reserved area
- @need_sz: needed bytes
- @resv_sz: reserved area size in bytes
- @offset: if not null, this will be filled with the offset of the return
head pointer from @shead
- @return: pointer to a new head where to start storing need_sz bytes, or
NULL if space could not be made available.- */
+struct _aarch64_ctx *get_starting_head(struct _aarch64_ctx *shead,
size_t need_sz, size_t resv_sz,size_t *offset)+{
- size_t offs = 0;
- struct _aarch64_ctx *head;
- head = get_terminator(shead, resv_sz, &offs);
- /* not found a terminator...no need to update offset if any */
- if (!head)
return head;- if (resv_sz - offs < need_sz) {
fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n",resv_sz - offs);head = get_header(shead, EXTRA_MAGIC, resv_sz, &offs);if (!head || resv_sz - offs < need_sz) {fprintf(stderr,"Failed to reclaim space on sigframe.\n");return NULL;}- }
- fprintf(stderr, "Available space:%zd\n", resv_sz - offs);
- if (offset)
*offset = offs;- return head;
+} diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.h b/tools/testing/selftests/arm64/signal/testcases/testcases.h index 04987f7870bc..ad884c135314 100644 --- a/tools/testing/selftests/arm64/signal/testcases/testcases.h +++ b/tools/testing/selftests/arm64/signal/testcases/testcases.h @@ -97,4 +97,8 @@ static inline void write_terminator_record(struct _aarch64_ctx *tail) tail->size = 0; } }
+struct _aarch64_ctx *get_starting_head(struct _aarch64_ctx *shead,
size_t need_sz, size_t resv_sz,size_t *offset);#endif
2.17.1
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