From 65073a67331de3d2cce35607807ddec284e75e81 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 31 Jan 2018 12:58:56 +0100 Subject: bpf: fix null pointer deref in bpf_prog_test_run_xdp syzkaller was able to generate the following XDP program ... (18) r0 = 0x0 (61) r5 = *(u32 *)(r1 +12) (04) (u32) r0 += (u32) 0 (95) exit ... and trigger a NULL pointer dereference in ___bpf_prog_run() via bpf_prog_test_run_xdp() where this was attempted to run. Reason is that recent xdp_rxq_info addition to XDP programs updated all drivers, but not bpf_prog_test_run_xdp(), where xdp_buff is set up. Thus when context rewriter does the deref on the netdev it's NULL at runtime. Fix it by using xdp_rxq from loopback dev. __netif_get_rx_queue() helper can also be reused in various other locations later on. Fixes: 02dd3291b2f0 ("bpf: finally expose xdp_rxq_info to XDP bpf-programs") Reported-by: syzbot+1eb094057b338eb1fc00@syzkaller.appspotmail.com Signed-off-by: Daniel Borkmann Cc: Jesper Dangaard Brouer Acked-by: Jesper Dangaard Brouer Signed-off-by: Alexei Starovoitov --- include/linux/netdevice.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include') diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 4c77f39ebd65..5eef6c8e2741 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3228,6 +3228,12 @@ static inline int netif_set_real_num_rx_queues(struct net_device *dev, } #endif +static inline struct netdev_rx_queue * +__netif_get_rx_queue(struct net_device *dev, unsigned int rxq) +{ + return dev->_rx + rxq; +} + #ifdef CONFIG_SYSFS static inline unsigned int get_netdev_rx_queue_index( struct netdev_rx_queue *queue) -- cgit v1.2.3