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 69F4B4399CD; Mon, 17 Aug 2026 14:52:53 +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=1786978374; cv=none; b=uTyaSq6nnUTLRMVOTlk/37GLsqbXiYjWpKuPsjT9ODaeCvOPN43bonfBZ7NpNaswOfirBMAvqDTpcJeSITFG6hoenNO+5U/EhjNMwigKtjmYQ3X2fUulFXcXl3F0OXen9gxYFJ/7rjSKxtTRfcEDkWPFK91xMyTNbfOjR0ZMAjU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786978374; c=relaxed/simple; bh=fnQLT1RTnZvVoV7Rc1/JCsOI7RiebtUBfLgcIkvMryk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LSK5vjQNTZgwvWOGJ/vUhVoecYR1Agt2UFHTlo+F3ODfySk2xFUk5qc7SU/CpCQiOyQ7mubtrP3tPHOTYsqLpaqN/EGgKp8izHlJY3aGybCNhZKKIoby0OnK5vc3FoC+LTIt40R35Vno0NWVbM4A2ujHkzWzS7bCPqW9AwvnG00= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=djY2Wm5r; 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="djY2Wm5r" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C46081F000E9; Mon, 17 Aug 2026 14:52:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786978373; bh=BqktnZBT3WcGeGSMOPkbp27/T3BkpmXL+Rf76TirbCA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=djY2Wm5rzRufExY50bcNxqoPDnyOppdr2hvAFPQhtQIJxcGkq0B6CLG4mhI1r1Tcq v7nIZl2qv6tZxhxCnudcJVPmxaUcBVjNSFSVTmmEmZvGh0w0GOXuKcBjDfsujPNxd2 XZA8Ab+RqkdOxSPAQCAUPFqX/QY/lCS9vL0/fYiA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yiyang Chen , Daniel Wade , Shung-Hsi Yu , Eduard Zingerman , Sasha Levin Subject: [PATCH 6.6 015/156] bpf: Preserve pointer state for commuted arithmetic Date: Mon, 17 Aug 2026 15:32:29 +0200 Message-ID: <20260817132535.235606052@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132534.666299318@linuxfoundation.org> References: <20260817132534.666299318@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yiyang Chen [ Upstream commit a4c6f804b44c5c790269b25e0e61cf4e9f117c86 ] When scalar += pointer is handled in adjust_ptr_min_max_vals(), the destination register inherits the pointer state from the source pointer. Copying only selected fields is fragile because pointer provenance is tracked by several bpf_reg_state fields. Use the caller's temporary offset register to preserve the scalar operand while replacing the destination with the full pointer state. This preserves the frame number for PTR_TO_STACK registers and keeps parent identity fields consistent. Fixes: f4d7e40a5b71 ("bpf: introduce function calls (verification)") Signed-off-by: Yiyang Chen Tested-by: Daniel Wade Acked-by: Shung-Hsi Yu Link: https://patch.msgid.link/20260729-c3-035-public-bpf-v4-v4-2-8ee297e2346b@mails.tsinghua.edu.cn Signed-off-by: Eduard Zingerman Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 5e094c12fc94c..ad679bc42427c 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12657,11 +12657,12 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, break; } - /* In case of 'scalar += pointer', dst_reg inherits pointer type and id. - * The id may be overwritten later if we create a new variable offset. + /* For 'scalar += pointer', dst_reg inherits the complete pointer + * register state. Individual fields may be adjusted later by pointer + * arithmetic. Callers guarantee that below does not overwrite off_reg. */ - dst_reg->type = ptr_reg->type; - dst_reg->id = ptr_reg->id; + if (dst_reg != ptr_reg) + *dst_reg = *ptr_reg; if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) || !check_reg_sane_offset(env, ptr_reg, ptr_reg->type)) @@ -12729,7 +12730,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, } break; case BPF_SUB: - if (dst_reg == off_reg) { + if (dst_reg != ptr_reg) { /* scalar -= pointer. Creates an unknown scalar */ verbose(env, "R%d tried to subtract pointer from scalar\n", dst); @@ -13588,8 +13589,8 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, err = mark_chain_precision(env, insn->dst_reg); if (err) return err; - return adjust_ptr_min_max_vals(env, insn, - src_reg, dst_reg); + off_reg = *dst_reg; + return adjust_ptr_min_max_vals(env, insn, src_reg, &off_reg); } } else if (ptr_reg) { /* pointer += scalar */ -- 2.53.0