From 9f32bfec545c30aae5ee7c2908e4c471d671482d Mon Sep 17 00:00:00 2001 From: KaFai Wan Date: Mon, 3 Nov 2025 14:31:08 +0800 Subject: [PATCH] selftests/bpf: Add test for conditional jumps on same scalar register Add test cases to verify the correctness of the BPF verifier's branch analysis when conditional jumps are performed on the same scalar register. And make sure that JGT does not trigger verifier BUG. Signed-off-by: KaFai Wan Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20251103063108.1111764-3-kafai.wan@linux.dev Signed-off-by: Alexei Starovoitov --- .../selftests/bpf/progs/verifier_bounds.c | 154 ++++++++++++++++++ 1 file changed, 154 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_bounds.c b/tools/testing/selftests/bpf/progs/verifier_bounds.c index 0a72e0228ea9a..411a18437d7ea 100644 --- a/tools/testing/selftests/bpf/progs/verifier_bounds.c +++ b/tools/testing/selftests/bpf/progs/verifier_bounds.c @@ -1709,4 +1709,158 @@ __naked void jeq_disagreeing_tnums(void *ctx) : __clobber_all); } +SEC("socket") +__description("conditional jump on same register, branch taken") +__not_msg("20: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__retval(0) __flag(BPF_F_TEST_REG_INVARIANTS) +__naked void condition_jump_on_same_register(void *ctx) +{ + asm volatile(" \ + call %[bpf_get_prandom_u32]; \ + w8 = 0x80000000; \ + r0 &= r8; \ + if r0 == r0 goto +1; \ + goto l1_%=; \ + if r0 >= r0 goto +1; \ + goto l1_%=; \ + if r0 s>= r0 goto +1; \ + goto l1_%=; \ + if r0 <= r0 goto +1; \ + goto l1_%=; \ + if r0 s<= r0 goto +1; \ + goto l1_%=; \ + if r0 != r0 goto l1_%=; \ + if r0 > r0 goto l1_%=; \ + if r0 s> r0 goto l1_%=; \ + if r0 < r0 goto l1_%=; \ + if r0 s< r0 goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, constant value branch taken") +__not_msg("7: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__retval(0) __flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_1(void *ctx) +{ + asm volatile(" \ + r0 = 0; \ + if r0 & r0 goto l1_%=; \ + r0 = 1; \ + if r0 & r0 goto +1; \ + goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, scalar value branch taken") +__not_msg("12: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__retval(0) __flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_2(void *ctx) +{ + asm volatile(" \ + /* range [1;2] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x1; \ + r0 += 1; \ + if r0 & r0 goto +1; \ + goto l1_%=; \ + /* range [-2;-1] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x1; \ + r0 -= 2; \ + if r0 & r0 goto +1; \ + goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, scalar value unknown branch 1") +__msg("3: (b7) r0 = 0 {{.*}} R0=0") +__msg("5: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_3(void *ctx) +{ + asm volatile(" \ + /* range [0;1] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x1; \ + if r0 & r0 goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, scalar value unknown branch 2") +__msg("4: (b7) r0 = 0 {{.*}} R0=0") +__msg("6: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_4(void *ctx) +{ + asm volatile(" \ + /* range [-1;0] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x1; \ + r0 -= 1; \ + if r0 & r0 goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, scalar value unknown branch 3") +__msg("4: (b7) r0 = 0 {{.*}} R0=0") +__msg("6: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_5(void *ctx) +{ + asm volatile(" \ + /* range [-1;1] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x2; \ + r0 -= 1; \ + if r0 & r0 goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + char _license[] SEC("license") = "GPL"; -- 2.47.3