3 files changed, 35 insertions, 12 deletions

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 6702a6a0bbb5..d51e1bb781cf 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -139,23 +139,32 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
 	return false;
 }
 
-struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
+struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
+						 struct inode *inode, u32 mask,
 						 const struct path *path)
 {
 	struct fanotify_event_info *event;
+	gfp_t gfp = GFP_KERNEL;
+
+	/*
+	 * For queues with unlimited length lost events are not expected and
+	 * can possibly have security implications. Avoid losing events when
+	 * memory is short.
+	 */
+	if (group->max_events == UINT_MAX)
+		gfp |= __GFP_NOFAIL;
 
 	if (fanotify_is_perm_event(mask)) {
 		struct fanotify_perm_event_info *pevent;
 
-		pevent = kmem_cache_alloc(fanotify_perm_event_cachep,
-					  GFP_KERNEL);
+		pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
 		if (!pevent)
 			return NULL;
 		event = &pevent->fae;
 		pevent->response = 0;
 		goto init;
 	}
-	event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL);
+	event = kmem_cache_alloc(fanotify_event_cachep, gfp);
 	if (!event)
 		return NULL;
 init: __maybe_unused
@@ -210,10 +219,17 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 			return 0;
 	}
 
-	event = fanotify_alloc_event(inode, mask, data);
+	event = fanotify_alloc_event(group, inode, mask, data);
 	ret = -ENOMEM;
-	if (unlikely(!event))
+	if (unlikely(!event)) {
+		/*
+		 * We don't queue overflow events for permission events as
+		 * there the access is denied and so no event is in fact lost.
+		 */
+		if (!fanotify_is_perm_event(mask))
+			fsnotify_queue_overflow(group);
 		goto finish;
+	}
 
 	fsn_event = &event->fse;
 	ret = fsnotify_add_event(group, fsn_event, fanotify_merge);
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 256d9d1ddea9..8609ba06f474 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -52,5 +52,6 @@ static inline struct fanotify_event_info *FANOTIFY_E(struct fsnotify_event *fse)
 	return container_of(fse, struct fanotify_event_info, fse);
 }
 
-struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
+struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
+						 struct inode *inode, u32 mask,
 						 const struct path *path);
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index c07eb3d655ea..ec4d8c59d0e3 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -757,7 +757,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 	group->fanotify_data.user = user;
 	atomic_inc(&user->fanotify_listeners);
 
-	oevent = fanotify_alloc_event(NULL, FS_Q_OVERFLOW, NULL);
+	oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL);
 	if (unlikely(!oevent)) {
 		fd = -ENOMEM;
 		goto out_destroy_group;
@@ -820,9 +820,8 @@ out_destroy_group:
 	return fd;
 }
 
-SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
-			      __u64, mask, int, dfd,
-			      const char  __user *, pathname)
+static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
+			    int dfd, const char  __user *pathname)
 {
 	struct inode *inode = NULL;
 	struct vfsmount *mnt = NULL;
@@ -928,13 +927,20 @@ fput_and_out:
 	return ret;
 }
 
+SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
+			      __u64, mask, int, dfd,
+			      const char  __user *, pathname)
+{
+	return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname);
+}
+
 #ifdef CONFIG_COMPAT
 COMPAT_SYSCALL_DEFINE6(fanotify_mark,
 				int, fanotify_fd, unsigned int, flags,
 				__u32, mask0, __u32, mask1, int, dfd,
 				const char  __user *, pathname)
 {
-	return sys_fanotify_mark(fanotify_fd, flags,
+	return do_fanotify_mark(fanotify_fd, flags,
 #ifdef __BIG_ENDIAN
 				((__u64)mask0 << 32) | mask1,
 #else