From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 121F71B4F1F for ; Fri, 3 Jul 2026 11:27:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783078031; cv=none; b=c/02QvHlo6YppDGl/IHjWphceL9bN5tP3MHvMA1ramlOqzMJQ/HqpPMcFeEs0Iy2Vm2fdrWJSZ18x536BBa4zgDVF8f6etjfjvVlx/pIKurEIBsnwLBOpkknlrLn9krhXXet5OI9zmXPGtYlmPX4CZR8P+iIHBy3WhkyymqpMAY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783078031; c=relaxed/simple; bh=7TZzsqMFbtcgc+w5SoueN6NnlsZVcur7+/g0tDCWPXg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=IQfWnpBl/tZa7a22LIg38KRqU4HmHVIDyLCJXwVOguW2vkn+aNoJebuMlF1baMccrYHOo7w30tN/Rw5LPxQL5qHearANx7/DPQY9VE1f82S/yT17LXyqs1HnyAqQ1hQrtN4AZRcjFk2tSLFN1/lsrZf5drOiY3ciFES5J8aqmK8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=eIdm/gXm; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=tRCoxWYP; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eIdm/gXm"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="tRCoxWYP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783078025; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=dquujKaEWXj9SeOR2cw//kdvyk2bjQlGJyeh7Df3DyQ=; b=eIdm/gXm3iY8BdEaZYDgpNxQclAT2ltsGoRQFeYmSUaqUWVxnlkrO2MdHlUy/59iVxtHlm 84KMqmN52bIVaDQphHqjbusUrAQNa5xpwh2LzmTCwqMEEn3r/E8VEWPl3s3nkf0Sk8go8h /VhBm8mQ8W9FShnd6E5gh1SOleYo6JU= Received: from mail-pl1-f197.google.com (mail-pl1-f197.google.com [209.85.214.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-581-UQV1zpCkNRyNkIdCwloyZA-1; Fri, 03 Jul 2026 07:27:02 -0400 X-MC-Unique: UQV1zpCkNRyNkIdCwloyZA-1 X-Mimecast-MFC-AGG-ID: UQV1zpCkNRyNkIdCwloyZA_1783078021 Received: by mail-pl1-f197.google.com with SMTP id d9443c01a7336-2c825562f8bso9448775ad.2 for ; Fri, 03 Jul 2026 04:27:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1783078021; x=1783682821; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=dquujKaEWXj9SeOR2cw//kdvyk2bjQlGJyeh7Df3DyQ=; b=tRCoxWYPlE5d5t3BHjAFklAIa8tfB02OGSjJy/GcnowcQCE1Yj3e0O0H5+94VCtnGs LjPjJmykCdLRVJdztYqyylo2Gm1fME5qX1PECnp1G3HQjVs33E/2KmRlNAgl3xuka/YU FWuHE6tZxZh5MaKQ3PUMTSfqxmRGytqZRdmojqAIhKlB2Cn+tPmIElSi+yxeEqVFBTth vJ8gLSKe/7wtOlbgbPNItmqB1rYk4p6aIRXPsM5PUfMWhWgw0lhJgt2jHSrCl6g0FiGb O+MrWqlROYXrndBc1OYzOsbqj94DoMw2XKljRBxDzPBd4IBjbjjkgk2z2QEQCtwwYWkO jQqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783078021; x=1783682821; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=dquujKaEWXj9SeOR2cw//kdvyk2bjQlGJyeh7Df3DyQ=; b=DuzeXX/VapZg9kyKfnSCbh+2uohSz//U4hsQOXirh0NTcFeRZoFvL2AVV8gHlMhNVG 9bEC0kbGNdAdul+B4lAtm9q1KyLVcrUw9atBhzUXh7zSrbm35uP1Lv83KzvgJ1+v9Wyq N1VNQuusL33SMLvJy+QOGzj4ANw8+BUg7XcuineQmCXduqVq95uCQG5rDkTSBKun1SHa yqdSCHlh8gWzWZ/1HteI5OkmAqc2ngFks/CJfENfwLAiinR7OvjnWZirnZrlkOnoh8KW zop680rsXHmK3VL/IZ1V8RWzVEM9feSZ6ez9epz7Fp3LiWRRe/Tkq4vhwxHlXdeCarI+ iKnA== X-Forwarded-Encrypted: i=1; AHgh+Rpk3EJh+wrx8Fl693SPdSLKiOh8D0jggzmiZgWIug4SlVnmtGDHDXuteOjMyw89r9QTscrwb/ikebG9O4vEwhM=@vger.kernel.org X-Gm-Message-State: AOJu0YzgujPhWK/EBbwYAekV5GVHcbmvJsKV7QngSxE0nhkTrdohvMVe AWlTD+8Csgsf5pDltVhp4DpgErA4CXlJt6iJSr7Unr3jc49HrYEW6HHp+tNk0U+ipE4q7Or3ARn bjLqSzzghMYGipX6vWfRwB+A99uYlgkjtamzXe5TTPzYgQuM65clcA0I5IjjBEZYzROYslw== X-Gm-Gg: AfdE7ck4SyJ+JkK03XKgwLEPxEoIo0eIYWkwq05kiPQq/S5cL+LlHnAO283UTFuo67z zd2ziKfLHDSztw4jAUsoYaKJsWEL8wW8Fdh4cRApwnYmJSyYVbUKNqjtg9urv+XRTlnrGnpRod7 Za1OTCeDZ13u4T5Fx1d+XrUJsIRghGyqF914xinJqaYIGwUeLGaSOXkrbfpmYCu5XIuQBivY/uL 1jTN/EuPGqAvLgKgdjleqb3m04PijchybxmpkDR7P3vQT7l2ie9KK9NZMse7dZOsy9NNJY6s8vT 3owWLZZiAj3fqAY6VWpyOVGJX2EECWJLUVi5cIlBGJZgdOZ9HF23MHr/k2Jjx8TAmLajbWlmue+ kDPBhVt41Q4EuSV9G2Xj7vyer7vyxsWKQ6Zd4IjzLMVOWovqWXA== X-Received: by 2002:a17:902:e54c:b0:2c9:adbb:5862 with SMTP id d9443c01a7336-2ca7e8b686fmr102173485ad.45.1783078021229; Fri, 03 Jul 2026 04:27:01 -0700 (PDT) X-Received: by 2002:a17:902:e54c:b0:2c9:adbb:5862 with SMTP id d9443c01a7336-2ca7e8b686fmr102173215ad.45.1783078020656; Fri, 03 Jul 2026 04:27:00 -0700 (PDT) Received: from localhost.localdomain (122-63-67-56.mobile.spark.co.nz. [122.63.67.56]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2cad6f260acsm8227305ad.6.2026.07.03.04.26.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Jul 2026 04:27:00 -0700 (PDT) From: Tao Liu To: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, bhe@redhat.com, zohar@linux.ibm.com, roberto.sassu@huawei.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, linux-integrity@vger.kernel.org, pratyush@kernel.org, Markus.Elfring@web.de, kernel-janitors@vger.kernel.org, jarkko@kernel.org, Tao Liu , stable@vger.kernel.org, Nutty Liu Subject: [PATCH v4] riscv: Prevent NULL pointer dereference in machine_kexec_prepare Date: Fri, 3 Jul 2026 23:15:31 +1200 Message-ID: <20260703111530.91285-2-ltao@redhat.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A NULL pointer dereference issue is noticed in riscv's machine_kexec_prepare(), where image->segment[i].buf might be NULL and copied unchecked. The NULL buf comes from ima_add_kexec_buffer(), where kbuf is added by kexec_add_buffer(), but kbuf.buffer is NULL, then it is copied without a check in machine_kexec_prepare(). Relevant path: kexec_file_load -> kimage_file_alloc_init() -> kimage_file_prepare_segments() -> ima_add_kexec_buffer() -> kexec_add_buffer() -> machine_kexec_prepare() -> memcpy() Address this by adding a check before the data copy attempt. Fixes: b7fb4d78a6ad ("RISC-V: use memcpy for kexec_file mode") Cc: stable@vger.kernel.org Closes: https://lore.kernel.org/kexec/CAO7dBbVftLUhd2qrh7hmijTB3PEPfZAhykCGqEfrPoOcSrrj-w@mail.gmail.com/ Acked-by: Baoquan He Acked-by: Pratyush Yadav Reviewed-by: Nutty Liu Signed-off-by: Tao Liu --- v4 -> v3: 1) Remove code comment. 2) Replace (buf == NULL) to (!buf). 3) Reword commit message. link to v1: https://lore.kernel.org/linux-riscv/20260529032739.13264-2-ltao@redhat.com/ link to v2: https://lore.kernel.org/linux-riscv/20260627222602.23594-2-ltao@redhat.com/ link to v3: https://lore.kernel.org/linux-riscv/20260701025732.66330-2-ltao@redhat.com/ --- arch/riscv/kernel/machine_kexec.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_kexec.c index 2306ce3e5f22..738df176ff6f 100644 --- a/arch/riscv/kernel/machine_kexec.c +++ b/arch/riscv/kernel/machine_kexec.c @@ -41,6 +41,9 @@ machine_kexec_prepare(struct kimage *image) if (image->segment[i].memsz <= sizeof(fdt)) continue; + if (!image->segment[i].buf) + continue; + if (image->file_mode) memcpy(&fdt, image->segment[i].buf, sizeof(fdt)); else if (copy_from_user(&fdt, image->segment[i].buf, sizeof(fdt))) -- 2.54.0