smoverlay/app-emulation/vmware-modules/files/329-03-vmmon-check-presence-of-file_operations-poll.patch

From 70ed9dd2ec64c09fbd0de27dcb10f9948a2b212a Mon Sep 17 00:00:00 2001
From: Michal Kubecek <mkubecek@suse.cz>
Date: Mon, 20 Aug 2018 07:46:13 +0200
Subject: [PATCH] vmmon: check presence of file_operations::poll()

Commit 11c5ad0ec441 ("eventpoll: switch to ->poll_mask") in v4.18-rc1, made
eventpoll switch from ->poll() to ->poll_mask(), resulting in a null
pointer dereference as vmmon calls the callback directly without checking
its availability.

Rather than calling the callback directly (which would result in null
pointer dereference), use vfs_poll() wrapper. As this wrapper is only
available since 4.18-rc1 cycle as well, provide a copy to use when building
against older kernels.

Note: even if the commit revealing the problem was reverted in 4.18-rc3
(and is unlikely to go back in the same form) so that vmmon no longer
crashes with 4.18 kernel, calling the callback without a check is a bad
practice so let's keep the patch in place.
---
 vmmon-only/include/compat_poll.h | 30 ++++++++++++++++++++++++++++++
 vmmon-only/linux/hostif.c        |  3 ++-
 2 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 vmmon-only/include/compat_poll.h

diff --git a/vmmon-only/include/compat_poll.h b/vmmon-only/include/compat_poll.h
new file mode 100644
index 0000000..562cdb6
--- /dev/null
+++ b/vmmon-only/include/compat_poll.h
@@ -0,0 +1,30 @@
+#ifndef __COMPAT_POLL_H__
+#define __COMPAT_POLL_H__
+
+#include <linux/poll.h>
+
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 18, 0))
+
+#ifndef __poll_t
+typedef unsigned int __poll_t;
+#endif
+
+static inline __poll_t compat_vfs_poll(struct file *file,
+				       struct poll_table_struct *pt)
+{
+	if (unlikely(!file->f_op->poll))
+		return DEFAULT_POLLMASK;
+	return file->f_op->poll(file, pt);
+}
+
+#else
+
+static inline __poll_t compat_vfs_poll(struct file *file,
+				       struct poll_table_struct *pt)
+{
+	return vfs_poll(file, pt);
+}
+
+#endif
+
+#endif /* __COMPAT_POLL_H__ */
diff --git a/vmmon-only/linux/hostif.c b/vmmon-only/linux/hostif.c
index 21758c2..af4b1d9 100644
--- a/vmmon-only/linux/hostif.c
+++ b/vmmon-only/linux/hostif.c
@@ -74,6 +74,7 @@
 
 #include "pgtbl.h"
 #include "versioned_atomic.h"
+#include "compat_poll.h"
 
 #if !defined(CONFIG_HIGH_RES_TIMERS)
 #error CONFIG_HIGH_RES_TIMERS required for acceptable performance
@@ -2570,7 +2571,7 @@ HostIF_SemaphoreWait(VMDriver *vm,   // IN:
 
       poll_initwait(&table);
       current->state = TASK_INTERRUPTIBLE;
-      mask = file->f_op->poll(file, &table.pt);
+      mask = compat_vfs_poll(file, &table.pt);
       if (!(mask & (POLLIN | POLLERR | POLLHUP))) {
          vm->vmhost->vcpuSemaTask[vcpuid] = current;
          schedule_timeout(timeoutms * HZ / 1000);  // convert to Hz
-- 
2.19.0