From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f41.google.com (mail-pj1-f41.google.com [209.85.216.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F422B492E4C for ; Wed, 9 Sep 2026 00:37:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788914235; cv=none; b=jN8vQ9ja+2lCzmdDR+Nh+MsCKWFCNjCDh5w4bcNpbpSyzDzAe/L6FT4GzHurd6KGi1Rz6LeaHAogfaDV3soxYrQSl/0/RKj22mx/JPI1h1dgQZsjcIXXbW8vmfE/UgRTbPDIl1ojFutAOrV52z0uZiJ1YVZ+ofRgi+ChtgbbCgI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788914235; c=relaxed/simple; bh=ZQ26WuN/2uDNusaBnSlD83HCZx/Czvc7ZEkPnGbepS0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rQlOzJGo/LT9NwVej3uZykHBXUnAcA9a/YOBTj0yt+eubrsq2/n9VM/+86ORcpiQ3u+YaQFhS/KCUgJ0jH/7GzvI3in6GG+8kYkSSOUCpuvnZ3TiHjrT0oY2MY7SIgWbye7KPqu5QN95/wDxrbnRpHTJh3gz619bfdsgCcbE5n0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=GSUadF2x; arc=none smtp.client-ip=209.85.216.41 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="GSUadF2x" Received: by mail-pj1-f41.google.com with SMTP id 98e67ed59e1d1-398a5aad413so4183967a91.3 for ; Tue, 08 Sep 2026 17:37:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1788914233; x=1789519033; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=PrbS3BESBt65p0R6Xy9pWvWwpzxrdANSE+CV32PeomU=; b=GSUadF2xdCRDpMY8p9PEOYYO1Y+ua973eVYwUK6pjlQeVATWp63na11UWDSzkaaOLk P4aPNi7Xf5C0Jxh9lkPUScAVJeSjd3Cq+paHoTz2yWTPW5WjVxrsIExDLehLHkJbUXTx wMENmRN2glhG7teqZIlSXaRMEXEfq7307JHBsXsU9OPyKt40nooj8NltqTezVM/7SI5D NxCZg1q8VGsFQZWNPkAzsTTuEtCqJlwDmQvIms2mwNJVWjy9oG+nVMGsClMv/qPj1Rfo jOWpIro+nZRDaJsQC0JIUqMHTABMBu96LCm3ix5252CvSd0bhoL0B1dziO7g7Xyb3MW5 u9XA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788914233; x=1789519033; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=PrbS3BESBt65p0R6Xy9pWvWwpzxrdANSE+CV32PeomU=; b=rRezenlTXMYfyQVBOmXuIKdcj3dWXeAVtCYbeAHJgG3kNYqiyg6viJ7dPyjI+eYqci uZD23to0QD2tTtk5DXro9LK93Q4uiAbSn79nJmnFXn/Ey7zMabTZRRd2DVWlIAhe2NK3 0McHu/5lCwdZdqf99QtPSmjLJaCFBQ7n1vlad3k5cf9i4cW9iALcIcdNvCSTaiFNrHL+ oCJoP/rT+Uyv1f3iJXnjPbxeW7ZsQn8YrYt0dwwVb0lKnVgOMGVCq8JEOqBAKf2g7mTl DiSSnb2ib6TywuRX+dhUP9HG8sLMwuSlcjBweVg5BwxSoVu5/2pL/BkSGL/5syHImZ8v rGig== X-Forwarded-Encrypted: i=1; AKwUvBxmy4Z9TsSSa/9s+pQD3X7rvBUDXVan4B6f7wphUMtnMBuvIlnRWLiyJN/5XapQ3QWBuaYkRPXyuXdCglw=@vger.kernel.org X-Gm-Message-State: AFuF++mniHxO06OvN8W8fyYDfTvpM/B0v71+NkMXTW/8KilT+ye5vX8d O53sn5vVwG9tzuayl+I6w3bqS49n3Y/q7JLi1cZchArQO/9NYbFwaZ7k X-Gm-Gg: AYBFou23kOYQsnaH+Xj0Xr47sCBdHl0OCTEHw3syXfM4/q/GtDEzZbP1oeUSAiYjR28 MBopNlzWhGm0EvafpQ6jM38V/O/v0TlUEG8G2r0cQb3TdIDig56ovil/UMd8/qcdBb3FkdvclsI p06J10DTm+6F74sL8mZ7GbWaHjwoEecn6aC5aRVvbaluvNRinWVEAl0kGpE0y17Kw7RpLdU/Gfw NBI7diUszouXMmcaEJHD6PWiNQ2ZxLMJQbvOxamCTpcRyYQ85dKGZ5boZlOfH0qkSIJyziKrzjF eG+ayfspRhf1mB+7NVBdJdHTCvmfxRuRPtPyrH/2cMbOjIufENa+gLaM3KZAoJ3LJIxMTPctkkt 23jwTdRIL2sFr/jzL0EDNXt6VxmFu5CfqWnevg2UQrdapTIE+paXmvAgari/X+SliX9T9JWgeLp QpqAaned9E6iaYOq3pQNg2vgwnh2Zu4FN6zLq3w/m61tTkN8tf8CA4RpawvegI X-Received: by 2002:a17:90b:2749:b0:398:d292:e6d5 with SMTP id 98e67ed59e1d1-39b26304385mr49122061a91.24.1788914233189; Tue, 08 Sep 2026 17:37:13 -0700 (PDT) Received: from localhost ([2400:ac40:62f:1b67:ddd8:990d:9d6f:13b8]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39b083e4fafsm34284184a91.1.2026.09.08.17.37.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Sep 2026 17:37:12 -0700 (PDT) From: Coiby Xu To: kexec@lists.infradead.org Cc: Andrew Morton , Sourabh Jain , Baoquan He , Dave Young , Pratyush Yadav , Will Deacon , linux-arm-kernel@lists.infradead.org, Jinjie Ruan , Mike Rapoport , Pasha Tatashin , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v5 3/9] crash_dump: Disallow writing to dm-crypt configfs during kexec_file_load syscall Date: Wed, 9 Sep 2026 08:36:45 +0800 Message-ID: <20260909003657.1570544-4-coiby.xu@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909003657.1570544-1-coiby.xu@gmail.com> References: <20260909003657.1570544-1-coiby.xu@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit If writing to the configfs group happens concurrently during kexec_file_load syscall, it may lead to the following issues, - buffer overflow if dm-crypt keys are added after allocation - stale total_keys if dm-crypt keys are removed during iteration - keys_header will not be freed if config/crash_dm_crypt_key/reuse is set true So hold config_keys_subsys.su_mutex for the entire sequence during the kexec_file_load syscall to ensure a consistent snapshot. To have serial access to config/crash_dm_crypt_key/reuse, use the kexec lock as we also need to access kexec_crash_image serially. Fixes: 479e58549b0f ("crash_dump: store dm crypt keys in kdump reserved memory") Suggested-by: Sourabh Jain Signed-off-by: Coiby Xu --- kernel/crash_dump_dm_crypt.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index 3a416933979f..580534d43b66 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -7,6 +7,7 @@ #include #include #include +#include "kexec_internal.h" #define KEY_NUM_MAX 128 /* maximum dm crypt keys */ #define KEY_SIZE_MAX 256 /* maximum dm crypt key size */ @@ -306,14 +307,20 @@ static ssize_t config_keys_reuse_store(struct config_item *item, bool val; int r; + if (!kexec_trylock()) { + pr_warn("Failed to acquire the kexec lock\n"); + return -EBUSY; + } + + r = -EINVAL; if (!kexec_crash_image || !kexec_crash_image->dm_crypt_keys_addr) { kexec_dprintk( "dm-crypt keys haven't be saved to crash-reserved memory\n"); - return -EINVAL; + goto unlock; } if (kstrtobool(page, &val) || !val) - return -EINVAL; + goto unlock; if (is_dm_key_reused) { pr_info("Already got dm-crypt keys, please continue with kexec_file_load syscall\n"); @@ -321,12 +328,15 @@ static ssize_t config_keys_reuse_store(struct config_item *item, r = get_keys_from_kdump_reserved_memory(); if (r) { pr_warn("Failed to get dm-crypt keys from reserved memory\n"); - return r; + goto unlock; } is_dm_key_reused = true; } - return count; + r = count; +unlock: + kexec_unlock(); + return r; } CONFIGFS_ATTR(config_keys_, reuse); @@ -443,15 +453,17 @@ int crash_load_dm_crypt_keys(struct kimage *image) int r = 0; if (!is_dm_key_reused) { + mutex_lock(&config_keys_subsys.su_mutex); + if (key_count <= 0) { kexec_dprintk("No dm-crypt keys\n"); r = 0; - goto out; + goto unlock; } r = build_keys_header(); if (r) - goto out; + goto unlock; } /* @@ -478,6 +490,9 @@ int crash_load_dm_crypt_keys(struct kimage *image) "Loaded dm crypt keys to kexec_buffer bufsz=0x%lx memsz=0x%lx\n", kbuf.bufsz, kbuf.memsz); +unlock: + mutex_unlock(&config_keys_subsys.su_mutex); + out: is_dm_key_reused = false; return r; -- 2.55.0