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authorDaniel Borkmann <daniel@iogearbox.net>2018-01-31 12:58:56 +0100
committerAlexei Starovoitov <ast@kernel.org>2018-02-01 07:43:56 -0800
commit65073a67331de3d2cce35607807ddec284e75e81 (patch)
treeaa39697a25f7b47548ca227b13d866558c9b98ce /tools/testing
parent62a06994ced17f295fc51ea0815580ee7ccb668d (diff)
downloadlinux-65073a67331de3d2cce35607807ddec284e75e81.tar.bz2
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 <daniel@iogearbox.net> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/testing')
-rw-r--r--tools/testing/selftests/bpf/test_verifier.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 697bd83de295..c0f16e93f9bd 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,