From: Maxim Mikityanskiy maxim@isovalent.com
When a range check is performed on a register that was 32-bit spilled to the stack, the IDs of the two instances of the register are the same, so the range should also be the same.
Signed-off-by: Maxim Mikityanskiy maxim@isovalent.com Acked-by: Eduard Zingerman eddyz87@gmail.com --- .../selftests/bpf/progs/verifier_spill_fill.c | 31 +++++++++++++++++++ 1 file changed, 31 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c index 848f2930f599..f303ac19cf41 100644 --- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c +++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c @@ -735,4 +735,35 @@ __naked void stack_load_preserves_const_precision_subreg(void) : __clobber_common); }
+SEC("xdp") +__description("32-bit spilled reg range should be tracked") +__success __retval(0) +__naked void spill_32bit_range_track(void) +{ + asm volatile(" \ + call %[bpf_ktime_get_ns]; \ + /* Make r0 bounded. */ \ + r0 &= 65535; \ + /* Assign an ID to r0. */ \ + r1 = r0; \ + /* 32-bit spill r0 to stack. */ \ + *(u32*)(r10 - 8) = r0; \ + /* Boundary check on r0. */ \ + if r0 < 1 goto l0_%=; \ + /* 32-bit fill r1 from stack. */ \ + r1 = *(u32*)(r10 - 8); \ + /* r1 == r0 => r1 >= 1 always. */ \ + if r1 >= 1 goto l0_%=; \ + /* Dead branch: the verifier should prune it. \ + * Do an invalid memory access if the verifier \ + * follows it. \ + */ \ + r0 = *(u64*)(r9 + 0); \ +l0_%=: r0 = 0; \ + exit; \ +" : + : __imm(bpf_ktime_get_ns) + : __clobber_all); +} + char _license[] SEC("license") = "GPL";