[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 <wolf0403@hotmail.com>, and
feedback from John McCutchan <john@johnmccutchan.com>.
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 <npiggin@suse.de>
Acked-by: "John McCutchan" <john@johnmccutchan.com>
Cc: Ryan <wolf0403@hotmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/inotify_user.c b/fs/inotify_user.c
index 55f6da5..9f2224f 100644
--- a/fs/inotify_user.c
+++ b/fs/inotify_user.c
@@ -455,8 +455,16 @@
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;