From 7fea700e04bd3f424c2d836e98425782f97b494e Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 8 Jun 2024 14:06:16 +0200 Subject: zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING kernel_wait4() doesn't sleep and returns -EINTR if there is no eligible child and signal_pending() is true. That is why zap_pid_ns_processes() clears TIF_SIGPENDING but this is not enough, it should also clear TIF_NOTIFY_SIGNAL to make signal_pending() return false and avoid a busy-wait loop. Link: https://lkml.kernel.org/r/20240608120616.GB7947@redhat.com Fixes: 12db8b690010 ("entry: Add support for TIF_NOTIFY_SIGNAL") Signed-off-by: Oleg Nesterov Reported-by: Rachel Menge Closes: https://lore.kernel.org/all/1386cd49-36d0-4a5c-85e9-bc42056a5a38@linux.microsoft.com/ Reviewed-by: Boqun Feng Tested-by: Wei Fu Reviewed-by: Jens Axboe Cc: Allen Pais Cc: Christian Brauner Cc: Frederic Weisbecker Cc: Joel Fernandes (Google) Cc: Joel Granados Cc: Josh Triplett Cc: Lai Jiangshan Cc: Mateusz Guzik Cc: Mathieu Desnoyers Cc: Mike Christie Cc: Neeraj Upadhyay Cc: Paul E. McKenney Cc: Steven Rostedt (Google) Cc: Zqiang Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- kernel/pid_namespace.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index dc48fecfa1dc..25f3cf679b35 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -218,6 +218,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) */ do { clear_thread_flag(TIF_SIGPENDING); + clear_thread_flag(TIF_NOTIFY_SIGNAL); rc = kernel_wait4(-1, NULL, __WALL, NULL); } while (rc != -ECHILD); -- cgit v1.2.3 From c1558bc57b8e5b4da5d821537cd30e2e660861d8 Mon Sep 17 00:00:00 2001 From: Peter Oberparleiter Date: Mon, 10 Jun 2024 11:27:43 +0200 Subject: gcov: add support for GCC 14 Using gcov on kernels compiled with GCC 14 results in truncated 16-byte long .gcda files with no usable data. To fix this, update GCOV_COUNTERS to match the value defined by GCC 14. Tested with GCC versions 14.1.0 and 13.2.0. Link: https://lkml.kernel.org/r/20240610092743.1609845-1-oberpar@linux.ibm.com Signed-off-by: Peter Oberparleiter Reported-by: Allison Henderson Reported-by: Chuck Lever III Tested-by: Chuck Lever Cc: Signed-off-by: Andrew Morton --- kernel/gcov/gcc_4_7.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/gcov/gcc_4_7.c b/kernel/gcov/gcc_4_7.c index 74a4ef1da9ad..fd75b4a484d7 100644 --- a/kernel/gcov/gcc_4_7.c +++ b/kernel/gcov/gcc_4_7.c @@ -18,7 +18,9 @@ #include #include "gcov.h" -#if (__GNUC__ >= 10) +#if (__GNUC__ >= 14) +#define GCOV_COUNTERS 9 +#elif (__GNUC__ >= 10) #define GCOV_COUNTERS 8 #elif (__GNUC__ >= 7) #define GCOV_COUNTERS 9 -- cgit v1.2.3 From 01c8f9806bde438ca1c8cbbc439f0a14a6694f6c Mon Sep 17 00:00:00 2001 From: Aleksandr Nogikh Date: Tue, 11 Jun 2024 15:32:29 +0200 Subject: kcov: don't lose track of remote references during softirqs In kcov_remote_start()/kcov_remote_stop(), we swap the previous KCOV metadata of the current task into a per-CPU variable. However, the kcov_mode_enabled(mode) check is not sufficient in the case of remote KCOV coverage: current->kcov_mode always remains KCOV_MODE_DISABLED for remote KCOV objects. If the original task that has invoked the KCOV_REMOTE_ENABLE ioctl happens to get interrupted and kcov_remote_start() is called, it ultimately leads to kcov_remote_stop() NOT restoring the original KCOV reference. So when the task exits, all registered remote KCOV handles remain active forever. The most uncomfortable effect (at least for syzkaller) is that the bug prevents the reuse of the same /sys/kernel/debug/kcov descriptor. If we obtain it in the parent process and then e.g. drop some capabilities and continuously fork to execute individual programs, at some point current->kcov of the forked process is lost, kcov_task_exit() takes no action, and all KCOV_REMOTE_ENABLE ioctls calls from subsequent forks fail. And, yes, the efficiency is also affected if we keep on losing remote kcov objects. a) kcov_remote_map keeps on growing forever. b) (If I'm not mistaken), we're also not freeing the memory referenced by kcov->area. Fix it by introducing a special kcov_mode that is assigned to the task that owns a KCOV remote object. It makes kcov_mode_enabled() return true and yet does not trigger coverage collection in __sanitizer_cov_trace_pc() and write_comp_data(). [nogikh@google.com: replace WRITE_ONCE() with an ordinary assignment] Link: https://lkml.kernel.org/r/20240614171221.2837584-1-nogikh@google.com Link: https://lkml.kernel.org/r/20240611133229.527822-1-nogikh@google.com Fixes: 5ff3b30ab57d ("kcov: collect coverage from interrupts") Signed-off-by: Aleksandr Nogikh Reviewed-by: Dmitry Vyukov Reviewed-by: Andrey Konovalov Tested-by: Andrey Konovalov Cc: Alexander Potapenko Cc: Arnd Bergmann Cc: Marco Elver Cc: Signed-off-by: Andrew Morton --- kernel/kcov.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/kcov.c b/kernel/kcov.c index c3124f6d5536..f0a69d402066 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -632,6 +632,7 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd, return -EINVAL; kcov->mode = mode; t->kcov = kcov; + t->kcov_mode = KCOV_MODE_REMOTE; kcov->t = t; kcov->remote = true; kcov->remote_size = remote_arg->area_size; -- cgit v1.2.3