diff --git a/include/linux/cnum.h b/include/linux/cnum.h index a7259b105b45..49b7d0c7645d 100644 --- a/include/linux/cnum.h +++ b/include/linux/cnum.h @@ -48,6 +48,7 @@ bool cnum32_is_const(struct cnum32 cnum); bool cnum32_is_empty(struct cnum32 cnum); struct cnum32 cnum32_add(struct cnum32 a, struct cnum32 b); struct cnum32 cnum32_negate(struct cnum32 a); +bool cnum32_is_subset(struct cnum32 outer, struct cnum32 inner); /* Same as cnum32 but for 64-bit ranges */ struct cnum64 { @@ -73,6 +74,7 @@ bool cnum64_is_const(struct cnum64 cnum); bool cnum64_is_empty(struct cnum64 cnum); struct cnum64 cnum64_add(struct cnum64 a, struct cnum64 b); struct cnum64 cnum64_negate(struct cnum64 a); +bool cnum64_is_subset(struct cnum64 outer, struct cnum64 inner); struct cnum32 cnum32_from_cnum64(struct cnum64 cnum); struct cnum64 cnum64_cnum32_intersect(struct cnum64 a, struct cnum32 b); diff --git a/kernel/bpf/cnum_defs.h b/kernel/bpf/cnum_defs.h index 3ebd8f723dbb..1f232138b6e9 100644 --- a/kernel/bpf/cnum_defs.h +++ b/kernel/bpf/cnum_defs.h @@ -220,6 +220,20 @@ bool FN(is_const)(struct cnum_t cnum) return cnum.size == 0; } +bool FN(is_subset)(struct cnum_t bigger, struct cnum_t smaller) +{ + if (FN(is_empty(smaller))) + return true; + if (FN(is_empty(bigger))) + return false; + /* rotate both arcs such that 'bigger' starts at origin, hence does not overflow */ + smaller.base -= bigger.base; + bigger.base = 0; + if (FN(urange_overflow)(smaller) && bigger.size < UT_MAX) + return false; + return smaller.base + smaller.size <= bigger.size; +} + #undef EMPTY #undef cnum_t #undef ut diff --git a/kernel/bpf/states.c b/kernel/bpf/states.c index a78ae891b743..bd9c22945050 100644 --- a/kernel/bpf/states.c +++ b/kernel/bpf/states.c @@ -2,6 +2,7 @@ /* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ #include #include +#include #include #define verbose(env, fmt, args...) bpf_verifier_log_write(env, fmt, ##args) @@ -301,14 +302,8 @@ int bpf_update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_s static bool range_within(const struct bpf_reg_state *old, const struct bpf_reg_state *cur) { - return reg_umin(old) <= reg_umin(cur) && - reg_umax(old) >= reg_umax(cur) && - reg_smin(old) <= reg_smin(cur) && - reg_smax(old) >= reg_smax(cur) && - reg_u32_min(old) <= reg_u32_min(cur) && - reg_u32_max(old) >= reg_u32_max(cur) && - reg_s32_min(old) <= reg_s32_min(cur) && - reg_s32_max(old) >= reg_s32_max(cur); + return cnum64_is_subset(old->r64, cur->r64) && + cnum32_is_subset(old->r32, cur->r32); } /* If in the old state two registers had the same id, then they need to have diff --git a/tools/testing/selftests/bpf/progs/verifier_bounds.c b/tools/testing/selftests/bpf/progs/verifier_bounds.c index 5dd243e653c9..a3e4c0945137 100644 --- a/tools/testing/selftests/bpf/progs/verifier_bounds.c +++ b/tools/testing/selftests/bpf/progs/verifier_bounds.c @@ -2267,4 +2267,31 @@ __naked void deduce64_from_32_wrapping_32bit(void) : __clobber_all); } +/* Check that range_within() compares cnum ranges, not min/max projections. */ +SEC("socket") +__failure __msg("div by zero") +__flag(BPF_F_TEST_STATE_FREQ) +__naked void range_within_cnum_cross_both_boundaries(void) +{ + asm volatile (" \ + call %[bpf_get_prandom_u32]; \ + r1 = 0x80000020; \ + if r0 > r1 goto 1f; \ + r0 += 0x7FFFFFF0; /* PATH 1 */ \ + goto 2f; \ +1: call %[bpf_get_prandom_u32]; /* PATH 2 */ \ + if r0 < 0x100 goto 3f; \ + if r0 > 0x200 goto 3f; \ +2: /* PATH 1: r0 ∈ [0x7FFFFFF0, U32_MAX] ∪ [0, 0x10] */ \ + /* PATH 2: r0 ∈ [0x100, 0x200] */ \ + if r0 != 0x100 goto 3f; /* True only on PATH 2 */ \ + r0 /= 0; \ +3: exit; \ + " + :: __imm(bpf_map_lookup_elem), + __imm_addr(map_hash_8b), + __imm(bpf_get_prandom_u32) + : __clobber_all); +} + char _license[] SEC("license") = "GPL";