| Message ID | 20180131115856.2965-1-daniel@iogearbox.net |
|---|---|
| State | Accepted, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf,v2] bpf: fix null pointer deref in bpf_prog_test_run_xdp | expand |
On Wed, 31 Jan 2018 12:58:56 +0100 Daniel Borkmann <daniel@iogearbox.net> wrote: > 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 <daniel@iogearbox.net> > Cc: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
On Wed, Jan 31, 2018 at 12:58:56PM +0100, Daniel Borkmann wrote: > 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 <daniel@iogearbox.net> > Cc: Jesper Dangaard Brouer <brouer@redhat.com> > --- > v1 -> v2: > - Rename netif_get_rx_queue() into __netif_get_rx_queue(). > > [ Note: Needs to wait till Linus pulled Dave's net-next so > the affected commit lands in bpf tree. ] Applied to bpf tree, Thank you Daniel.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index cd46d3d..d589a26 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) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index a86e668..2ced486 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -151,6 +151,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, { u32 size = kattr->test.data_size_in; u32 repeat = kattr->test.repeat; + struct netdev_rx_queue *rxqueue; struct xdp_buff xdp = {}; u32 retval, duration; void *data; @@ -165,6 +166,9 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, xdp.data_meta = xdp.data; xdp.data_end = xdp.data + size; + rxqueue = __netif_get_rx_queue(current->nsproxy->net_ns->loopback_dev, 0); + xdp.rxq = &rxqueue->xdp_rxq; + retval = bpf_test_run(prog, &xdp, repeat, &duration); if (xdp.data != data + XDP_PACKET_HEADROOM + NET_IP_ALIGN) size = xdp.data_end - xdp.data; diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 697bd83..c0f16e9 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -7780,6 +7780,20 @@ static struct bpf_test tests[] = { .result = REJECT, }, { + "XDP, using ifindex from netdev", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, + offsetof(struct xdp_md, ingress_ifindex)), + BPF_JMP_IMM(BPF_JLT, BPF_REG_2, 1, 1), + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }, + .result = ACCEPT, + .prog_type = BPF_PROG_TYPE_XDP, + .retval = 1, + }, + { "meta access, test1", .insns = { BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
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 <daniel@iogearbox.net> Cc: Jesper Dangaard Brouer <brouer@redhat.com> --- v1 -> v2: - Rename netif_get_rx_queue() into __netif_get_rx_queue(). [ Note: Needs to wait till Linus pulled Dave's net-next so the affected commit lands in bpf tree. ] include/linux/netdevice.h | 6 ++++++ net/bpf/test_run.c | 4 ++++ tools/testing/selftests/bpf/test_verifier.c | 14 ++++++++++++++ 3 files changed, 24 insertions(+)