Backport upstream fix for QTBUG-86319

qt5-qtbase.spec

@@ -49,7 +49,7 @@ BuildRequires: pkgconfig(libsystemd)
 Name:    qt5-qtbase
 Summary: Qt5 - QtBase components
 Version: 5.15.1
-Release: 6%{?dist}
+Release: 7%{?dist}
 
 # See LGPL_EXCEPTIONS.txt, for exception details
 License: LGPLv2 with exceptions or GPLv3 with exceptions
@@ -129,6 +129,8 @@ Patch90: %{name}-gcc11.patch
 ## upstream patches
 Patch100: qtbase-emit-qscreen-geometry-changed-when-logical-dpi-changes.patch
 
+Patch101: qtbase-QTBUG-86319.patch
+
 # Do not check any files in %%{_qt5_plugindir}/platformthemes/ for requires.
 # Those themes are there for platform integration. If the required libraries are
 # not there, the platform to integrate with isn't either. Then Qt will just
@@ -389,6 +391,7 @@ Qt5 libraries used for drawing widgets and OpenGL items.
 
 ## upstream patches
 %patch100 -p1 -b .emit-qscreen-geometry-changed-when-logical-dpi-changes
+%patch101 -p1
 
 # move some bundled libs to ensure they're not accidentally used
 pushd src/3rdparty
@@ -1046,6 +1049,9 @@ fi
 
 
 %changelog
+* Tue Nov 03 2020 Sandro Mani <manisandro@gmail.com> - 5.15.1-7
+- Backport upstream fix for QTBUG-86319
+
 * Sun Oct 18 2020 Jeff Law <law@redhat.com> - 5.15.1-6
 - Fix missing #includes for gcc-11
 

qtbase-QTBUG-86319.patch

@@ -0,0 +1,73 @@
+From a82032351c921c3d5d57122aca57b47f83f9b9d1 Mon Sep 17 00:00:00 2001
+From: Thiago Macieira <thiago.macieira@intel.com>
+Date: Thu, 10 Sep 2020 13:30:59 -0700
+Subject: [PATCH] forkfd/Linux: ask clone() to use the SIGCHLD as the
+ termination signal
+
+Because of these lines in the Linux kernel (kernel/fork.c, see [1][3]):
+
+		if (clone_flags & CLONE_VFORK)
+			trace = PTRACE_EVENT_VFORK;
+		else if (args->exit_signal != SIGCHLD)
+			trace = PTRACE_EVENT_CLONE;
+		else
+			trace = PTRACE_EVENT_FORK;
+
+Without CLONE_VFORK (which we can't use), if the exit signal isn't
+SIGCHLD, the debugger will get a PTRACE_EVENT_CLONE, which makes it
+think the process we're starting is a thread, not a new process. Both
+gdb and lldb remain attached to the child and when it later performs an
+execve(), they get mightily confused. See gdb bug report[5].
+
+The idea of not having an exit_signal was so that no SIGCHLD would be
+delivered to the parent process in the first place. That way, some
+misguided SIGCHLD handler (*cough* GLib *cough*) wouldn't reap our
+processes. Unfortunately, what I didn't realize was that the kernel
+sends SIGCHLD anyway (see [2][4]), so this defensive measure didn't
+actually work. Consequently, we can pass SIGCHLD to clone() and get the
+debuggers working again.
+
+[ChangeLog][Linux] Fixed an issue that would cause debugging a Qt
+application that uses QProcess to confuse both gdb and lldb if
+the Linux kernel was version 5.4 or higher. Behavior outside of
+a debugging session was not affected.
+
+[1] https://code.woboq.org/linux/linux/kernel/fork.c.html#_do_fork
+[2] https://code.woboq.org/linux/linux/kernel/signal.c.html#do_notify_parent
+[3] https://elixir.bootlin.com/linux/v5.8/source/kernel/fork.c#L2432
+[4] https://elixir.bootlin.com/linux/v5.8/source/kernel/signal.c#L1925
+[5] https://sourceware.org/bugzilla/show_bug.cgi?id=26562
+
+Fixes: QTBUG-86319
+Change-Id: I2fc68c725ba649218bd9fffd1633863613537d42
+Reviewed-by: Dimitrios Apostolou <jimis@qt.io>
+Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
+Reviewed-by: hjk <hjk@qt.io>
+(cherry picked from commit d1fc991c6e3c45a5f93c925d49e3fe77ce6ce455)
+Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
+---
+ src/3rdparty/forkfd/forkfd_linux.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/src/3rdparty/forkfd/forkfd_linux.c b/src/3rdparty/forkfd/forkfd_linux.c
+index 523fbca3ccc..ffe0e9a5e24 100644
+--- a/src/3rdparty/forkfd/forkfd_linux.c
++++ b/src/3rdparty/forkfd/forkfd_linux.c
+@@ -147,7 +147,7 @@ int system_forkfd(int flags, pid_t *ppid, int *system)
+     }
+ 
+     *system = 1;
+-    unsigned long cloneflags = CLONE_PIDFD;
++    unsigned long cloneflags = CLONE_PIDFD | SIGCHLD;
+     pid = sys_clone(cloneflags, &pidfd);
+     if (ppid)
+         *ppid = pid;
+@@ -171,7 +171,7 @@ int system_forkfd_wait(int ffd, struct forkfd_info *info, int ffdoptions, struct
+ {
+     siginfo_t si;
+     int ret;
+-    int options = __WALL | convertForkfdWaitFlagsToWaitFlags(ffdoptions);
++    int options = convertForkfdWaitFlagsToWaitFlags(ffdoptions);
+ 
+     if ((options & WNOHANG) == 0) {
+         /* check if the file descriptor is non-blocking */