Commit-ID: 403613432222549727e5d70cf44da8987653202a Gitweb: http://git.kernel.org/tip/403613432222549727e5d70cf44da8987653202a Author: Andy Lutomirski <l...@kernel.org> AuthorDate: Wed, 10 Feb 2016 14:15:26 -0800 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 17 Feb 2016 09:51:06 +0100
selftests/x86: Add a test for syscall restart under ptrace This catches a regression from the compat syscall rework. The 32-bit variant of this test currently fails. The issue is that, for a 32-bit tracer and a 32-bit tracee, GETREGS+SETREGS with no changes should be a no-op. It currently isn't a no-op if RAX indicates signal restart, because the high bits get cleared and the kernel loses track of the restart state. Reported-by: Robert O'Callahan <rob...@ocallahan.org> Signed-off-by: Andy Lutomirski <l...@kernel.org> Cc: Al Viro <v...@zeniv.linux.org.uk> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Shuah Khan <shua...@osg.samsung.com> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/c4040b40b5b4a37ed31375a69b683f753ec6788a.1455142412.git.l...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- tools/testing/selftests/x86/ptrace_syscall.c | 126 +++++++++++++++++++++++++++ 1 file changed, 126 insertions(+) diff --git a/tools/testing/selftests/x86/ptrace_syscall.c b/tools/testing/selftests/x86/ptrace_syscall.c index c6a0acc..4214567 100644 --- a/tools/testing/selftests/x86/ptrace_syscall.c +++ b/tools/testing/selftests/x86/ptrace_syscall.c @@ -103,6 +103,17 @@ static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), err(1, "sigaction"); } +static void setsigign(int sig, int flags) +{ + struct sigaction sa; + memset(&sa, 0, sizeof(sa)); + sa.sa_sigaction = (void *)SIG_IGN; + sa.sa_flags = flags; + sigemptyset(&sa.sa_mask); + if (sigaction(sig, &sa, 0)) + err(1, "sigaction"); +} + static void clearhandler(int sig) { struct sigaction sa; @@ -277,6 +288,119 @@ static void test_ptrace_syscall_restart(void) } } +static void test_restart_under_ptrace(void) +{ + printf("[RUN]\tkernel syscall restart under ptrace\n"); + pid_t chld = fork(); + if (chld < 0) + err(1, "fork"); + + if (chld == 0) { + if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0) + err(1, "PTRACE_TRACEME"); + + printf("\tChild will take a nap until signaled\n"); + setsigign(SIGUSR1, SA_RESTART); + raise(SIGSTOP); + + syscall(SYS_pause, 0, 0, 0, 0, 0, 0); + _exit(0); + } + + int status; + + /* Wait for SIGSTOP. */ + if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status)) + err(1, "waitpid"); + + struct user_regs_struct regs; + + printf("[RUN]\tSYSCALL\n"); + if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0) + err(1, "PTRACE_SYSCALL"); + wait_trap(chld); + + /* We should be stopped at pause(2) entry. */ + + if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) + err(1, "PTRACE_GETREGS"); + + if (regs.user_syscall_nr != SYS_pause || + regs.user_arg0 != 0 || regs.user_arg1 != 0 || + regs.user_arg2 != 0 || regs.user_arg3 != 0 || + regs.user_arg4 != 0 || regs.user_arg5 != 0) { + printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); + nerrs++; + } else { + printf("[OK]\tInitial nr and args are correct\n"); + } + + /* Interrupt it. */ + kill(chld, SIGUSR1); + + /* Advance. We should be stopped at exit. */ + printf("[RUN]\tSYSCALL\n"); + if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0) + err(1, "PTRACE_SYSCALL"); + wait_trap(chld); + + if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) + err(1, "PTRACE_GETREGS"); + + if (regs.user_syscall_nr != SYS_pause || + regs.user_arg0 != 0 || regs.user_arg1 != 0 || + regs.user_arg2 != 0 || regs.user_arg3 != 0 || + regs.user_arg4 != 0 || regs.user_arg5 != 0) { + printf("[FAIL]\tArgs after SIGUSR1 are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); + nerrs++; + } else { + printf("[OK]\tArgs after SIGUSR1 are correct (ax = %ld)\n", + (long)regs.user_ax); + } + + /* Poke the regs back in. This must not break anything. */ + if (ptrace(PTRACE_SETREGS, chld, 0, ®s) != 0) + err(1, "PTRACE_SETREGS"); + + /* Catch the (ignored) SIGUSR1. */ + if (ptrace(PTRACE_CONT, chld, 0, 0) != 0) + err(1, "PTRACE_CONT"); + if (waitpid(chld, &status, 0) != chld) + err(1, "waitpid"); + if (!WIFSTOPPED(status)) { + printf("[FAIL]\tChild was stopped for SIGUSR1 (status = 0x%x)\n", status); + nerrs++; + } else { + printf("[OK]\tChild got SIGUSR1\n"); + } + + /* The next event should be pause(2) again. */ + printf("[RUN]\tStep again\n"); + if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0) + err(1, "PTRACE_SYSCALL"); + wait_trap(chld); + + /* We should be stopped at pause(2) entry. */ + + if (ptrace(PTRACE_GETREGS, chld, 0, ®s) != 0) + err(1, "PTRACE_GETREGS"); + + if (regs.user_syscall_nr != SYS_pause || + regs.user_arg0 != 0 || regs.user_arg1 != 0 || + regs.user_arg2 != 0 || regs.user_arg3 != 0 || + regs.user_arg4 != 0 || regs.user_arg5 != 0) { + printf("[FAIL]\tpause did not restart (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5); + nerrs++; + } else { + printf("[OK]\tpause(2) restarted correctly\n"); + } + + /* Kill it. */ + kill(chld, SIGKILL); + if (waitpid(chld, &status, 0) != chld) + err(1, "waitpid"); +} + int main() { printf("[RUN]\tCheck int80 return regs\n"); @@ -290,5 +414,7 @@ int main() test_ptrace_syscall_restart(); + test_restart_under_ptrace(); + return 0; }
