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Wed, 11 Feb 2026 14:31:59 -0800 (PST) Received: from ezingerman-fedora-PF4V722J.thefacebook.com ([2620:10d:c090:500::2:8141]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2ba9dcd0609sm2639306eec.16.2026.02.11.14.31.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Feb 2026 14:31:59 -0800 (PST) From: Eduard Zingerman To: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org Cc: daniel@iogearbox.net, martin.lau@linux.dev, kernel-team@fb.com, yonghong.song@linux.dev, eddyz87@gmail.com Subject: [PATCH bpf-next 1/3] bpf: split check_reg_sane_offset() in two parts Date: Wed, 11 Feb 2026 14:31:38 -0800 Message-ID: <20260211-ptrs-off-migration-v1-1-996c2a37b063@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260211-ptrs-off-migration-v1-0-996c2a37b063@gmail.com> References: <20260211-ptrs-off-migration-v1-0-996c2a37b063@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit check_reg_sane_offset() is used when verifying operations like: dst_reg += src_reg ^ ^ | '-------- scalar '------------------- pointer To verify range for both dst_reg and src_reg. Split it in two parts: - one to check a pointer offset - another to check scalar offset This would be useful for further refactoring. Signed-off-by: Eduard Zingerman --- kernel/bpf/verifier.c | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index edf5342b982f676567579ed6349ccd5391eee7c8..3bf72eacbec2407fc79e22f62098755415bdf61c 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14426,9 +14426,9 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, return 0; } -static bool check_reg_sane_offset(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, - enum bpf_reg_type type) +static bool check_reg_sane_offset_scalar(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + enum bpf_reg_type type) { bool known = tnum_is_const(reg->var_off); s64 val = reg->var_off.value; @@ -14440,12 +14440,6 @@ static bool check_reg_sane_offset(struct bpf_verifier_env *env, return false; } - if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) { - verbose(env, "%s pointer offset %d is not allowed\n", - reg_type_str(env, type), reg->off); - return false; - } - if (smin == S64_MIN) { verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n", reg_type_str(env, type)); @@ -14461,6 +14455,27 @@ static bool check_reg_sane_offset(struct bpf_verifier_env *env, return true; } +static bool check_reg_sane_offset_ptr(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, + enum bpf_reg_type type) +{ + s64 smin = reg->smin_value; + + if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) { + verbose(env, "%s pointer offset %d is not allowed\n", + reg_type_str(env, type), reg->off); + return false; + } + + if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) { + verbose(env, "%s pointer offset %lld is not allowed\n", + reg_type_str(env, type), smin); + return false; + } + + return true; +} + enum { REASON_BOUNDS = -1, REASON_TYPE = -2, @@ -14874,8 +14889,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, dst_reg->type = ptr_reg->type; dst_reg->id = ptr_reg->id; - if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) || - !check_reg_sane_offset(env, ptr_reg, ptr_reg->type)) + if (!check_reg_sane_offset_scalar(env, off_reg, ptr_reg->type) || + !check_reg_sane_offset_ptr(env, ptr_reg, ptr_reg->type)) return -EINVAL; /* pointer types do not carry 32-bit bounds at the moment. */ @@ -15004,7 +15019,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, return -EACCES; } - if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type)) + if (!check_reg_sane_offset_ptr(env, dst_reg, ptr_reg->type)) return -EINVAL; reg_bounds_sync(dst_reg); bounds_ret = sanitize_check_bounds(env, insn, dst_reg); -- 2.53.0