From f9e4acf3befd3b2903e01b3ef1bd344f03299826 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Mon, 12 Feb 2007 00:51:59 -0800 Subject: [PATCH] [PATCH] inotify: read return val fix Fix for inotify read bug (bugzilla.kernel.org #6999) Problem Description: When reading from an inotify device with an insufficient sized buffer, read(2) will return 0 with no errno set. This is because of an logically incorrect action from the user program thus should return an more logical value. My suggestion is return -EINVAL as for bind(2). This patch is based on the proposal from Ryan , and feedback from John McCutchan . Return -EINVAL if we have not passed in enough buffer space to read a single inotify event, rather than 0 which indicates that there is nothing to read. Signed-off-by: Nick Piggin Acked-by: "John McCutchan" Cc: Ryan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/inotify_user.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/inotify_user.c b/fs/inotify_user.c index 55f6da55b7c0..9f2224f65a18 100644 --- a/fs/inotify_user.c +++ b/fs/inotify_user.c @@ -455,8 +455,16 @@ static ssize_t inotify_read(struct file *file, char __user *buf, break; kevent = inotify_dev_get_event(dev); - if (event_size + kevent->event.len > count) + if (event_size + kevent->event.len > count) { + if (ret == 0 && count > 0) { + /* + * could not get a single event because we + * didn't have enough buffer space. + */ + ret = -EINVAL; + } break; + } if (copy_to_user(buf, &kevent->event, event_size)) { ret = -EFAULT; -- 2.39.5