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GET /api/patches/2215679/?format=api
{ "id": 2215679, "url": "http://patchwork.ozlabs.org/api/patches/2215679/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260325025904.2811960-9-ruanjinjie@huawei.com/", "project": { "id": 2, "url": "http://patchwork.ozlabs.org/api/projects/2/?format=api", "name": "Linux PPC development", "link_name": "linuxppc-dev", "list_id": "linuxppc-dev.lists.ozlabs.org", "list_email": "linuxppc-dev@lists.ozlabs.org", "web_url": "https://github.com/linuxppc/wiki/wiki", "scm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git", "webscm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/", "list_archive_url_format": "https://lore.kernel.org/linuxppc-dev/{}/", "commit_url_format": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id={}" }, "msgid": "<20260325025904.2811960-9-ruanjinjie@huawei.com>", "list_archive_url": "https://lore.kernel.org/linuxppc-dev/20260325025904.2811960-9-ruanjinjie@huawei.com/", "date": "2026-03-25T02:59:04", "name": "[v10,8/8] crash: Fix race condition between crash kernel loading and memory hotplug", "commit_ref": null, "pull_url": null, "state": "handled-elsewhere", "archived": false, "hash": "47194c9bbf1c0811b7ef776df32e43c8a44323b3", "submitter": { "id": 84791, "url": "http://patchwork.ozlabs.org/api/people/84791/?format=api", "name": "Jinjie Ruan", "email": "ruanjinjie@huawei.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260325025904.2811960-9-ruanjinjie@huawei.com/mbox/", "series": [ { "id": 497378, "url": "http://patchwork.ozlabs.org/api/series/497378/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=497378", "date": "2026-03-25T02:58:56", "name": "[v10,1/8] riscv: kexec_file: Fix crashk_low_res not exclude bug", "version": 10, "mbox": "http://patchwork.ozlabs.org/series/497378/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2215679/comments/", "check": "success", "checks": "http://patchwork.ozlabs.org/api/patches/2215679/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linuxppc-dev+bounces-18757-incoming=patchwork.ozlabs.org@lists.ozlabs.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linuxppc-dev@lists.ozlabs.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=huawei.com header.i=@huawei.com header.a=rsa-sha256\n header.s=dkim header.b=xqNJJTRY;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=112.213.38.117; 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a=rsa-sha256; d=huawei.com; s=dkim;\n\tc=relaxed/relaxed; q=dns/txt;\n\th=From;\n\tbh=8E4spcrmYqVzYUlBqOGzHHrelMM+VkOSD8iaO6+byhw=;\n\tb=xqNJJTRYyggCzXZzuIVa391GmVhP2M1AywiTzUCVIdevfMWk2W0+G2iNIudjPzgYPiCgaIuhE\n\t5THdqWRaQk7mWGN7AJ7Xy8EnMOPizyjjR001GpeKPLFi3V5PkCr2VJzvHZC7VITILAKNTbQjTE4\n\tda7qaeuWWHQjW0U1XLO75kc=", "From": "Jinjie Ruan <ruanjinjie@huawei.com>", "To": "<corbet@lwn.net>, <skhan@linuxfoundation.org>, <catalin.marinas@arm.com>,\n\t<will@kernel.org>, <chenhuacai@kernel.org>, <kernel@xen0n.name>,\n\t<maddy@linux.ibm.com>, <mpe@ellerman.id.au>, <npiggin@gmail.com>,\n\t<chleroy@kernel.org>, <pjw@kernel.org>, <palmer@dabbelt.com>,\n\t<aou@eecs.berkeley.edu>, <alex@ghiti.fr>, <tglx@kernel.org>,\n\t<mingo@redhat.com>, <bp@alien8.de>, <dave.hansen@linux.intel.com>,\n\t<hpa@zytor.com>, <robh@kernel.org>, <saravanak@kernel.org>,\n\t<akpm@linux-foundation.org>, <bhe@redhat.com>, <vgoyal@redhat.com>,\n\t<dyoung@redhat.com>, <rdunlap@infradead.org>, <peterz@infradead.org>,\n\t<pawan.kumar.gupta@linux.intel.com>, <feng.tang@linux.alibaba.com>,\n\t<dapeng1.mi@linux.intel.com>, <kees@kernel.org>, <elver@google.com>,\n\t<paulmck@kernel.org>, <lirongqing@baidu.com>, <ruanjinjie@huawei.com>,\n\t<rppt@kernel.org>, <ardb@kernel.org>, <leitao@debian.org>, <osandov@fb.com>,\n\t<cfsworks@gmail.com>, <tangyouling@kylinos.cn>, <sourabhjain@linux.ibm.com>,\n\t<ritesh.list@gmail.com>, <eajames@linux.ibm.com>,\n\t<songshuaishuai@tinylab.org>, <kevin.brodsky@arm.com>,\n\t<samuel.holland@sifive.com>, <vishal.moola@gmail.com>,\n\t<junhui.liu@pigmoral.tech>, <coxu@redhat.com>, <liaoyuanhong@vivo.com>,\n\t<jbohac@suse.cz>, <fuqiang.wang@easystack.cn>, <guoren@kernel.org>,\n\t<chenjiahao16@huawei.com>, <hbathini@linux.ibm.com>, <james.morse@arm.com>,\n\t<takahiro.akashi@linaro.org>, <lizhengyu3@huawei.com>, <x86@kernel.org>,\n\t<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,\n\t<linux-arm-kernel@lists.infradead.org>, <loongarch@lists.linux.dev>,\n\t<linuxppc-dev@lists.ozlabs.org>, <linux-riscv@lists.infradead.org>,\n\t<devicetree@vger.kernel.org>, <kexec@lists.infradead.org>", "Subject": "[PATCH v10 8/8] crash: Fix race condition between crash kernel\n loading and memory hotplug", "Date": "Wed, 25 Mar 2026 10:59:04 +0800", "Message-ID": "<20260325025904.2811960-9-ruanjinjie@huawei.com>", "X-Mailer": "git-send-email 2.34.1", "In-Reply-To": "<20260325025904.2811960-1-ruanjinjie@huawei.com>", "References": "<20260325025904.2811960-1-ruanjinjie@huawei.com>", "X-Mailing-List": "linuxppc-dev@lists.ozlabs.org", "List-Id": "<linuxppc-dev.lists.ozlabs.org>", "List-Help": "<mailto:linuxppc-dev+help@lists.ozlabs.org>", "List-Owner": "<mailto:linuxppc-dev+owner@lists.ozlabs.org>", "List-Post": "<mailto:linuxppc-dev@lists.ozlabs.org>", "List-Archive": "<https://lore.kernel.org/linuxppc-dev/>,\n <https://lists.ozlabs.org/pipermail/linuxppc-dev/>", "List-Subscribe": "<mailto:linuxppc-dev+subscribe@lists.ozlabs.org>,\n <mailto:linuxppc-dev+subscribe-digest@lists.ozlabs.org>,\n <mailto:linuxppc-dev+subscribe-nomail@lists.ozlabs.org>", "List-Unsubscribe": "<mailto:linuxppc-dev+unsubscribe@lists.ozlabs.org>", "Precedence": "list", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Content-Type": "text/plain", "X-Originating-IP": "[10.90.53.73]", "X-ClientProxiedBy": "kwepems100001.china.huawei.com (7.221.188.238) To\n dggpemf500011.china.huawei.com (7.185.36.131)", "X-Spam-Status": "No, score=-0.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID,\n\tDKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=disabled\n\tversion=4.0.1 OzLabs 8", "X-Spam-Checker-Version": "SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org" }, "content": "There is a race condition between the kexec_load() system call\n(crash kernel loading path) and memory hotplug operations that can lead\nto buffer overflow and potential kernel crash.\n\nDuring crash_prepare_headers(), the following steps occur:\n1. arch_get_system_nr_ranges() queries current memory ranges from memblock\n2. alloc_cmem() allocates buffer based on queried count\n3. arch_crash_populate_cmem() populates ranges from memblock\n\nIf memory hotplug occurs between step 1 and step 3, the number of ranges\ncan increase, causing out-of-bounds write when populating cmem->ranges[].\n\nThis happens because kexec_load() uses kexec_trylock (atomic_t) while\nmemory hotplug uses device_hotplug_lock (mutex), so they don't serialize\nwith each other.\n\nFix by adding lock_device_hotplug()/unlock_device_hotplug() around the\ncritical section in crash_prepare_headers(). The lock is only acquired\nwhen CONFIG_MEMORY_HOTPLUG is enabled to avoid overhead on systems without\nhotplug support.\n\nFixes: dd5f726076cc (\"kexec: support for kexec on panic using new system call\")\nFixes: 3751e728cef2 (\"arm64: kexec_file: add crash dump support\")\nFixes: 8acea455fafa (\"RISC-V: Support for kexec_file on panic\")\nFixes: 1bcca8620a91 (\"LoongArch: Add crash dump support for kexec_file\")\nSigned-off-by: Jinjie Ruan <ruanjinjie@huawei.com>\n---\n kernel/crash_core.c | 24 ++++++++++++++++++++----\n 1 file changed, 20 insertions(+), 4 deletions(-)", "diff": "diff --git a/kernel/crash_core.c b/kernel/crash_core.c\nindex 300d44ad5471..f01d03d42c67 100644\n--- a/kernel/crash_core.c\n+++ b/kernel/crash_core.c\n@@ -326,15 +326,25 @@ int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,\n \tstruct crash_mem *cmem;\n \tint ret;\n \n+\tif (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))\n+\t\tlock_device_hotplug();\n+\n \tmax_nr_ranges = arch_get_system_nr_ranges();\n-\tif (!max_nr_ranges)\n-\t\treturn -ENOMEM;\n+\tif (!max_nr_ranges) {\n+\t\tret = -ENOMEM;\n+\t\tgoto unlock;\n+\t}\n \n \tcmem = alloc_cmem(max_nr_ranges);\n-\tif (!cmem)\n-\t\treturn -ENOMEM;\n+\tif (!cmem) {\n+\t\tret = -ENOMEM;\n+\t\tgoto unlock;\n+\t}\n \n \tret = arch_crash_populate_cmem(cmem);\n+\tif (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))\n+\t\tunlock_device_hotplug();\n+\n \tif (ret)\n \t\tgoto out;\n \n@@ -355,6 +365,12 @@ int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,\n out:\n \tkvfree(cmem);\n \treturn ret;\n+\n+unlock:\n+\tif (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))\n+\t\tunlock_device_hotplug();\n+\n+\treturn ret;\n }\n \n /**\n", "prefixes": [ "v10", "8/8" ] }