* [PATCH] fanotify: fix -EOVERFLOW with large files on 64-bit
@ 2017-11-16 19:43 Stefan Nuernberger
2017-11-16 20:28 ` Greg KH
0 siblings, 1 reply; 2+ messages in thread
From: Stefan Nuernberger @ 2017-11-16 19:43 UTC (permalink / raw)
To: stable; +Cc: Amit Shah, David Woodhouse, Will Woods
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);
--
2.15.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] fanotify: fix -EOVERFLOW with large files on 64-bit
2017-11-16 19:43 [PATCH] fanotify: fix -EOVERFLOW with large files on 64-bit Stefan Nuernberger
@ 2017-11-16 20:28 ` Greg KH
0 siblings, 0 replies; 2+ messages in thread
From: Greg KH @ 2017-11-16 20:28 UTC (permalink / raw)
To: Stefan Nuernberger; +Cc: stable, Amit Shah, David Woodhouse, Will Woods
On Thu, Nov 16, 2017 at 08:43:53PM +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
3.10.y is end-of-life :(
See the front page of www.kernel.org for that list if you are curious.
thanks,
greg k-h
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2017-11-16 19:43 [PATCH] fanotify: fix -EOVERFLOW with large files on 64-bit Stefan Nuernberger
2017-11-16 20:28 ` Greg KH
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