From e1d794541b3f17c37f66d4134ee7c044fac4dc87 Mon Sep 17 00:00:00 2001 From: Harishankar Vishwanathan Date: Mon, 23 Jun 2025 00:03:57 -0400 Subject: [PATCH] selftests/bpf: Add testcases for BPF_ADD and BPF_SUB The previous commit improves the precision in scalar(32)_min_max_add, and scalar(32)_min_max_sub. The improvement in precision occurs in cases when all outcomes overflow or underflow, respectively. This commit adds selftests that exercise those cases. This commit also adds selftests for cases where the output register state bounds for u(32)_min/u(32)_max are conservatively set to unbounded (when there is partial overflow or underflow). Signed-off-by: Harishankar Vishwanathan Co-developed-by: Matan Shachnai Signed-off-by: Matan Shachnai Suggested-by: Eduard Zingerman Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250623040359.343235-3-harishankar.vishwanathan@gmail.com Signed-off-by: Alexei Starovoitov --- .../selftests/bpf/progs/verifier_bounds.c | 161 ++++++++++++++++++ 1 file changed, 161 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_bounds.c b/tools/testing/selftests/bpf/progs/verifier_bounds.c index 30e16153fdf14..e52a24e15b34a 100644 --- a/tools/testing/selftests/bpf/progs/verifier_bounds.c +++ b/tools/testing/selftests/bpf/progs/verifier_bounds.c @@ -1371,4 +1371,165 @@ __naked void mult_sign_ovf(void) __imm(bpf_skb_store_bytes) : __clobber_all); } + +SEC("socket") +__description("64-bit addition, all outcomes overflow") +__success __log_level(2) +__msg("5: (0f) r3 += r3 {{.*}} R3_w=scalar(umin=0x4000000000000000,umax=0xfffffffffffffffe)") +__retval(0) +__naked void add64_full_overflow(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r4 = r0;" + "r3 = 0xa000000000000000 ll;" + "r3 |= r4;" + "r3 += r3;" + "r0 = 0;" + "exit" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("64-bit addition, partial overflow, result in unbounded reg") +__success __log_level(2) +__msg("4: (0f) r3 += r3 {{.*}} R3_w=scalar()") +__retval(0) +__naked void add64_partial_overflow(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r4 = r0;" + "r3 = 2;" + "r3 |= r4;" + "r3 += r3;" + "r0 = 0;" + "exit" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("32-bit addition overflow, all outcomes overflow") +__success __log_level(2) +__msg("4: (0c) w3 += w3 {{.*}} R3_w=scalar(smin=umin=umin32=0x40000000,smax=umax=umax32=0xfffffffe,var_off=(0x0; 0xffffffff))") +__retval(0) +__naked void add32_full_overflow(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "w4 = w0;" + "w3 = 0xa0000000;" + "w3 |= w4;" + "w3 += w3;" + "r0 = 0;" + "exit" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("32-bit addition, partial overflow, result in unbounded u32 bounds") +__success __log_level(2) +__msg("4: (0c) w3 += w3 {{.*}} R3_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))") +__retval(0) +__naked void add32_partial_overflow(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "w4 = w0;" + "w3 = 2;" + "w3 |= w4;" + "w3 += w3;" + "r0 = 0;" + "exit" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("64-bit subtraction, all outcomes underflow") +__success __log_level(2) +__msg("6: (1f) r3 -= r1 {{.*}} R3_w=scalar(umin=1,umax=0x8000000000000000)") +__retval(0) +__naked void sub64_full_overflow(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r1 = r0;" + "r2 = 0x8000000000000000 ll;" + "r1 |= r2;" + "r3 = 0;" + "r3 -= r1;" + "r0 = 0;" + "exit" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("64-bit subtration, partial overflow, result in unbounded reg") +__success __log_level(2) +__msg("3: (1f) r3 -= r2 {{.*}} R3_w=scalar()") +__retval(0) +__naked void sub64_partial_overflow(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r3 = r0;" + "r2 = 1;" + "r3 -= r2;" + "r0 = 0;" + "exit" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("32-bit subtraction overflow, all outcomes underflow") +__success __log_level(2) +__msg("5: (1c) w3 -= w1 {{.*}} R3_w=scalar(smin=umin=umin32=1,smax=umax=umax32=0x80000000,var_off=(0x0; 0xffffffff))") +__retval(0) +__naked void sub32_full_overflow(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "w1 = w0;" + "w2 = 0x80000000;" + "w1 |= w2;" + "w3 = 0;" + "w3 -= w1;" + "r0 = 0;" + "exit" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("32-bit subtration, partial overflow, result in unbounded u32 bounds") +__success __log_level(2) +__msg("3: (1c) w3 -= w2 {{.*}} R3_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))") +__retval(0) +__naked void sub32_partial_overflow(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "w3 = w0;" + "w2 = 1;" + "w3 -= w2;" + "r0 = 0;" + "exit" + : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + char _license[] SEC("license") = "GPL"; -- 2.47.2