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Commit 7063efd3 authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
Browse files

tuntap: fix use after free during release 



After commit b196d88a ("tun: fix use after free for ptr_ring") we
need clean up tx ring during release(). But unfortunately, it tries to
do the cleanup blindly after socket were destroyed which will lead
another use-after-free. Fix this by doing the cleanup before dropping
the last reference of the socket in __tun_detach().

Reported-by: default avatarAndrei Vagin <avagin@virtuozzo.com>
Acked-by: default avatarAndrei Vagin <avagin@virtuozzo.com>
Fixes: b196d88a ("tun: fix use after free for ptr_ring")
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent fee8fb95

drivers/net/tun.c

+1 −1
Original line number Diff line number Diff line
@@ -729,6 +729,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean) 
		}

		if (tun)

			xdp_rxq_info_unreg(&tfile->xdp_rxq);

		ptr_ring_cleanup(&tfile->tx_ring, tun_ptr_free);

		sock_put(&tfile->sk);

	}

}
@@ -3245,7 +3246,6 @@ static int tun_chr_close(struct inode *inode, struct file *file) 
	struct tun_file *tfile = file->private_data;



	tun_detach(tfile, true);

	ptr_ring_cleanup(&tfile->tx_ring, tun_ptr_free);



	return 0;

}