(Adding bwh to CC - he maintains the 3.2 kernel.)On Do, 2017-11-16 at 20:43 +0100, Stefan Nuernberger wrote:
From: Will Woods wwoods@redhat.com
commit 1e2ee49f7f1b79f0b14884fe6a602f0411b39552 upstream.
On 64-bit systems, O_LARGEFILE is automatically added to flags inside the open() syscall (also openat(), blkdev_open(), etc). Userspace therefore defines O_LARGEFILE to be 0 - you can use it, but it's a no-op. Everything should be O_LARGEFILE by default.
But: when fanotify does create_fd() it uses dentry_open(), which skips all that. And userspace can't set O_LARGEFILE in fanotify_init() because it's defined to 0. So if fanotify gets an event regarding a large file, the read() will just fail with -EOVERFLOW.
This patch adds O_LARGEFILE to fanotify_init()'s event_f_flags on 64- bit systems, using the same test as open()/openat()/etc.
Addresses https://bugzilla.redhat.com/show_bug.cgi?id=696821
Signed-off-by: Will Woods wwoods@redhat.com Acked-by: Eric Paris eparis@redhat.com Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org
[snu: Backported to 3.2 / 3.10: adjusted context]
Signed-off-by: Stefan Nuernberger snu@amazon.com Reviewed-by: Pawel Wieczorkiewicz wipawel@amazon.de Reviewed-by: Simon Veith sveith@amazon.de
Cc: stable@vger.kernel.org # 3.2.x and 3.10.x
fs/notify/fanotify/fanotify_user.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index d57995e1cfd7..dd3d9d13a4c4 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -712,6 +712,9 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) group->fanotify_data.user = user; atomic_inc(&user->fanotify_listeners);
- if (force_o_largefile())
event_f_flags |= O_LARGEFILE;group->fanotify_data.f_flags = event_f_flags; #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS mutex_init(&group->fanotify_data.access_mutex);
Reviewed-by: Amit Shah aams@amazon.com
-- Amazon Development Center Germany GmbH Berlin - Dresden - Aachen main office: Krausenstr. 38, 10117 Berlin Geschaeftsfuehrer: Dr. Ralf Herbrich, Christian Schlaeger Ust-ID: DE289237879 Eingetragen am Amtsgericht Charlottenburg HRB 149173 B