[ Upstream commit 2803cf4379ed252894f046cb8812a48db35294e3 ]

v9fs_dir_readdir() could deadloop if a struct was sent with a size set
to -2

Link: http://lkml.kernel.org/r/1536134432-11997-1-git-send-email-asmadeus@codewreck.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88021Signed-off-by: NGertjan Halkes <gertjan@google.com>
Signed-off-by: NDominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: NSasha Levin <sashal@kernel.org>