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commitb196d88abaupstream. We used to initialize ptr_ring during TUNSETIFF, this is because its size depends on the tx_queue_len of netdevice. And we try to clean it up when socket were detached from netdevice. A race were spotted when trying to do uninit during a read which will lead a use after free for pointer ring. Solving this by always initialize a zero size ptr_ring in open() and do resizing during TUNSETIFF, and then we can safely do cleanup during close(). With this, there's no need for the workaround that was introduced by commit4df0bfc799("tun: fix a memory leak for tfile->tx_array"). Backport Note :- Comparison with the upstream patch: [1] A "semantic revert" of the changes made in 4df0bfc799("tun: fix a memory leak for tfile->tx_array").4df0bfc799was applied upstream, and then skb array was changed to use ptr_ring. The upstream patch then removes the changes introduced by4df0bfc799. This backport does the same; "revert" the changes made by4df0bfc799. [2] xdp_rxq_info_unreg() being called in relevant locations As xdp_rxq_info related patches are not present in 4.14, these changes are not needed in the backport. [3] An instance of ptr_ring_init needs to be replaced by skb_array_init Inside tun_attach() [4] ptr_ring_cleanup needs to be replaced by skb_array_cleanup Inside tun_chr_close() Note that the backport for7063efd33b("tuntap: fix use after free during release") needs to be applied on top of this patch. Reported-by: syzbot+e8b902c3c3fadf0a9dba@syzkaller.appspotmail.com Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Michael S. Tsirkin <mst@redhat.com> Fixes:1576d98605("tun: switch to use skb array for tx") Signed-off-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Zubin Mithra <zsm@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.