This is a note to let you know that I've just added the patch titled

selftests/x86/ptrace_syscall: Fix for yet more glibc interference

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: selftests-x86-ptrace_syscall-fix-for-yet-more-glibc-interference.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 4b0b37d4cc54b21a6ecad7271cbc850555869c62 Mon Sep 17 00:00:00 2001

From: Andy Lutomirski luto@kernel.org Date: Sat, 17 Mar 2018 08:25:07 -0700 Subject: selftests/x86/ptrace_syscall: Fix for yet more glibc interference

From: Andy Lutomirski luto@kernel.org

commit 4b0b37d4cc54b21a6ecad7271cbc850555869c62 upstream.

glibc keeps getting cleverer, and my version now turns raise() into more than one syscall. Since the test relies on ptrace seeing an exact set of syscalls, this breaks the test. Replace raise(SIGSTOP) with syscall(SYS_tgkill, ...) to force glibc to get out of our way.

Signed-off-by: Andy Lutomirski luto@kernel.org Cc: Borislav Petkov bp@alien8.de Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: linux-kselftest@vger.kernel.org Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/bc80338b453afa187bc5f895bd8e2c8d6e264da2.1521300271... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- tools/testing/selftests/x86/ptrace_syscall.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/tools/testing/selftests/x86/ptrace_syscall.c +++ b/tools/testing/selftests/x86/ptrace_syscall.c @@ -182,8 +182,10 @@ static void test_ptrace_syscall_restart( if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0) err(1, "PTRACE_TRACEME");

+ pid_t pid = getpid(), tid = syscall(SYS_gettid); + printf("\tChild will make one syscall\n"); - raise(SIGSTOP); + syscall(SYS_tgkill, pid, tid, SIGSTOP);

syscall(SYS_gettid, 10, 11, 12, 13, 14, 15); _exit(0); @@ -300,9 +302,11 @@ static void test_restart_under_ptrace(vo if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0) err(1, "PTRACE_TRACEME");

+ pid_t pid = getpid(), tid = syscall(SYS_gettid); + printf("\tChild will take a nap until signaled\n"); setsigign(SIGUSR1, SA_RESTART); - raise(SIGSTOP); + syscall(SYS_tgkill, pid, tid, SIGSTOP);

syscall(SYS_pause, 0, 0, 0, 0, 0, 0); _exit(0);

Patches currently in stable-queue which might be from luto@kernel.org are

queue-4.9/selftests-x86-ptrace_syscall-fix-for-yet-more-glibc-interference.patch queue-4.9/kvm-x86-fix-icebp-instruction-handling.patch