From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 809F54C10E1; Thu, 17 Sep 2026 15:40:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789659666; cv=none; b=hA8FBAcn0bCvLal/oO2dHSGshfYssULhbwYhhR+PBScwqCvEXioq0lkHlf7+UOImDb1jCbEB2+QWQAyyxz212/KE2Cb2byI6rWQNQhF6xk7vcilSgZ5cnzIIjgekiDrKlz3Kl/2EV0xqz3Pp9AOvFwM3VSqDJX04wygwN8oZz0c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789659666; c=relaxed/simple; bh=c/L4c2E5YFk989IwT5xfeNZXjXDaVoe8f4AwfSCLV2c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=t4XF2LDiT12AlPLnGj1Hbu2b95HwqbFcjF5qLGbWsDd+SLF492k6zu/AJcznKBSKMIF1GVHeVdX5P4J5SgbOwrMaWQh74AWuQufvd6sPrI8jUuUA5A+c894StpKooaIT4xPaU5kMF5y3qiIRDVU2elFrtm6t08R7N9d1lhaVZ1c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AAIpRplh; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="AAIpRplh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C141F1F00898; Thu, 17 Sep 2026 15:40:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789659655; bh=hS2uFiNccQPQ5fg+D6vzzfzuxvRtY3iSy/UOXTWMcxs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AAIpRplhs6IZOIz9/8fWJL/QMePTjsyGF5sy9iVKKNy+HaocSO+4SF+ZmfiKjKKkG 0szvJxmwJJ0cjWw/Q8zJ1uuZSDB/2l6W57iW3+BSSY0EMCY+Wfrzeux5x9uHu0Oq0Z F6m43sxJyWYYW6tOonm9u7DVaEggYyZ7UwqS3irs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eduard Zingerman , Alexei Starovoitov , Sasha Levin Subject: [PATCH 7.2 290/733] bpf: propagate mark_chain_precision() errors out of loop_flag_is_zero() Date: Thu, 17 Sep 2026 16:09:58 +0100 Message-ID: <20260917151358.630589941@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151350.597953846@linuxfoundation.org> References: <20260917151350.597953846@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eduard Zingerman [ Upstream commit 1d7f8f191c06f967a85922c4652dc33c132b585d ] Stop verification if mark_chain_precision() fails when called from loop_flag_is_zero(). No functional change intended for the paths where backtracking succeeds. Fixes: 1ade23711971 ("bpf: Inline calls to bpf_loop when callback is known") Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-9-0f5a360ff15d@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1b2df166e0849..54a4435f50fba 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10188,33 +10188,45 @@ static struct bpf_insn_aux_data *cur_aux(const struct bpf_verifier_env *env) return &env->insn_aux_data[env->insn_idx]; } -static bool loop_flag_is_zero(struct bpf_verifier_env *env) +/* Returns 1 if R4 is a known zero, 0 if it is not, a negative errno on error. */ +static int loop_flag_is_zero(struct bpf_verifier_env *env) { struct bpf_reg_state *reg = reg_state(env, BPF_REG_4); - bool reg_is_null = bpf_register_is_null(reg); + int err; - if (reg_is_null) - mark_chain_precision(env, BPF_REG_4); + if (!bpf_register_is_null(reg)) + return 0; - return reg_is_null; + err = mark_chain_precision(env, BPF_REG_4); + if (err) + return err; + return 1; } -static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno) +static int update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno) { struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state; + int flag_is_zero; if (!state->initialized) { + flag_is_zero = loop_flag_is_zero(env); + if (flag_is_zero < 0) + return flag_is_zero; state->initialized = 1; - state->fit_for_inline = loop_flag_is_zero(env); + state->fit_for_inline = flag_is_zero; state->callback_subprogno = subprogno; - return; + return 0; } if (!state->fit_for_inline) - return; + return 0; - state->fit_for_inline = (loop_flag_is_zero(env) && + flag_is_zero = loop_flag_is_zero(env); + if (flag_is_zero < 0) + return flag_is_zero; + state->fit_for_inline = (flag_is_zero && state->callback_subprogno == subprogno); + return 0; } /* Returns whether or not the given map can potentially elide @@ -10426,7 +10438,9 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn err = check_bpf_snprintf_call(env, regs); break; case BPF_FUNC_loop: - update_loop_inline_state(env, meta.subprogno); + err = update_loop_inline_state(env, meta.subprogno); + if (err) + return err; /* Verifier relies on R1 value to determine if bpf_loop() iteration * is finished, thus mark it precise. */ -- 2.53.0