diff options
Diffstat (limited to 'tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c')
-rw-r--r-- | tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c b/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c index 5905e036e0..a955a63582 100644 --- a/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c +++ b/tools/testing/selftests/bpf/progs/verifier_iterating_callbacks.c @@ -239,4 +239,74 @@ int bpf_loop_iter_limit_nested(void *unused) return 1000 * a + b + c; } +struct iter_limit_bug_ctx { + __u64 a; + __u64 b; + __u64 c; +}; + +static __naked void iter_limit_bug_cb(void) +{ + /* This is the same as C code below, but written + * in assembly to control which branches are fall-through. + * + * switch (bpf_get_prandom_u32()) { + * case 1: ctx->a = 42; break; + * case 2: ctx->b = 42; break; + * default: ctx->c = 42; break; + * } + */ + asm volatile ( + "r9 = r2;" + "call %[bpf_get_prandom_u32];" + "r1 = r0;" + "r2 = 42;" + "r0 = 0;" + "if r1 == 0x1 goto 1f;" + "if r1 == 0x2 goto 2f;" + "*(u64 *)(r9 + 16) = r2;" + "exit;" + "1: *(u64 *)(r9 + 0) = r2;" + "exit;" + "2: *(u64 *)(r9 + 8) = r2;" + "exit;" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all + ); +} + +SEC("tc") +__failure +__flag(BPF_F_TEST_STATE_FREQ) +int iter_limit_bug(struct __sk_buff *skb) +{ + struct iter_limit_bug_ctx ctx = { 7, 7, 7 }; + + bpf_loop(2, iter_limit_bug_cb, &ctx, 0); + + /* This is the same as C code below, + * written in assembly to guarantee checks order. + * + * if (ctx.a == 42 && ctx.b == 42 && ctx.c == 7) + * asm volatile("r1 /= 0;":::"r1"); + */ + asm volatile ( + "r1 = *(u64 *)%[ctx_a];" + "if r1 != 42 goto 1f;" + "r1 = *(u64 *)%[ctx_b];" + "if r1 != 42 goto 1f;" + "r1 = *(u64 *)%[ctx_c];" + "if r1 != 7 goto 1f;" + "r1 /= 0;" + "1:" + : + : [ctx_a]"m"(ctx.a), + [ctx_b]"m"(ctx.b), + [ctx_c]"m"(ctx.c) + : "r1" + ); + return 0; +} + char _license[] SEC("license") = "GPL"; |