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Bugzilla: 696821
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Upstream-status: Sent http://marc.info/?l=linux-kernel&m=139835974112096&w=2
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On 64-bit systems, O_LARGEFILE is automatically added to flags inside
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the open() syscall (also openat(), blkdev_open(), etc).
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Userspace therefore defines O_LARGEFILE to be 0 - you can use it,
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but it's a no-op. Everything should be O_LARGEFILE by default.
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But: when fanotify does create_fd() it uses dentry_open(), which skips
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all that. And userspace can't set O_LARGEFILE in fanotify_init() because
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it's defined to 0. So if fanotify gets an event regarding a large file,
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the read() will just fail with -EOVERFLOW.
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This patch adds O_LARGEFILE to fanotify_init()'s event_f_flags on 64-bit
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systems, using the same test as open()/openat()/etc.
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Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=696821
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Acked-by: Eric Paris <eparis@redhat.com>
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Signed-off-by: Will Woods <wwoods@redhat.com>
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---
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 fs/notify/fanotify/fanotify_user.c | 2 ++
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 1 file changed, 2 insertions(+)
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diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
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index 4e565c8..732648b 100644
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--- a/fs/notify/fanotify/fanotify_user.c
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+++ b/fs/notify/fanotify/fanotify_user.c
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@@ -698,6 +698,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
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 	}
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 	group->overflow_event = &oevent->fse;
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+	if (force_o_largefile())
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+		event_f_flags |= O_LARGEFILE;
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 	group->fanotify_data.f_flags = event_f_flags;
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 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
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 	spin_lock_init(&group->fanotify_data.access_lock);
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-- 
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1.9.0