When none of the registers have changed, don't flush them back. This can happen if the architecture uses a non-register way to change the syscall (e.g. arm64) , and a return value hasn't been written.
Signed-off-by: Kees Cook keescook@chromium.org --- tools/testing/selftests/seccomp/seccomp_bpf.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index d9346121b89b..2790d9cd50f4 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -1859,11 +1859,12 @@ int get_syscall(struct __test_metadata *_metadata, pid_t tracee) void change_syscall(struct __test_metadata *_metadata, pid_t tracee, int syscall, int result) { - ARCH_REGS regs; + ARCH_REGS orig, regs;
EXPECT_EQ(0, ARCH_GETREGS(regs)) { return; } + orig = regs;
SYSCALL_NUM_SET(regs, syscall);
@@ -1876,7 +1877,8 @@ void change_syscall(struct __test_metadata *_metadata, #endif
/* Flush any register changes made. */ - EXPECT_EQ(0, ARCH_SETREGS(regs)); + if (memcmp(&orig, ®s, sizeof(orig)) != 0) + EXPECT_EQ(0, ARCH_SETREGS(regs)); }
void tracer_seccomp(struct __test_metadata *_metadata, pid_t tracee,