diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 542e23fb19c7b..e4928846e7637 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15993,6 +15993,30 @@ static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_sta s64 smin2 = is_jmp32 ? (s64)reg2->s32_min_value : reg2->smin_value; s64 smax2 = is_jmp32 ? (s64)reg2->s32_max_value : reg2->smax_value; + if (reg1 == reg2) { + switch (opcode) { + case BPF_JGE: + case BPF_JLE: + case BPF_JSGE: + case BPF_JSLE: + case BPF_JEQ: + return 1; + case BPF_JGT: + case BPF_JLT: + case BPF_JSGT: + case BPF_JSLT: + case BPF_JNE: + return 0; + case BPF_JSET: + if (tnum_is_const(t1)) + return t1.value != 0; + else + return (smin1 <= 0 && smax1 >= 0) ? -1 : 1; + default: + return -1; + } + } + switch (opcode) { case BPF_JEQ: /* constants, umin/umax and smin/smax checks would be @@ -16439,6 +16463,13 @@ static int reg_set_min_max(struct bpf_verifier_env *env, if (false_reg1->type != SCALAR_VALUE || false_reg2->type != SCALAR_VALUE) return 0; + /* We compute branch direction for same SCALAR_VALUE registers in + * is_scalar_branch_taken(). For unknown branch directions (e.g., BPF_JSET) + * on the same registers, we don't need to adjust the min/max values. + */ + if (false_reg1 == false_reg2) + return 0; + /* fallthrough (FALSE) branch */ regs_refine_cond_op(false_reg1, false_reg2, rev_opcode(opcode), is_jmp32); reg_bounds_sync(false_reg1); diff --git a/tools/testing/selftests/bpf/progs/verifier_bounds.c b/tools/testing/selftests/bpf/progs/verifier_bounds.c index 0a72e0228ea9a..e975dc285db62 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";