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Fri, 01 May 2026 16:44:17 -0700 (PDT) From: Coiby Xu To: kexec@lists.infradead.org Cc: Andrew Morton , Sourabh Jain , Baoquan He , Dave Young , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Coiby Xu , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 3/9] crash_dump: Disallow writing to dm-crypt configfs during kexec_file_load syscall Date: Sat, 2 May 2026 07:43:32 +0800 Message-ID: <20260501234342.2518281-4-coiby.xu@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260501234342.2518281-1-coiby.xu@gmail.com> References: <20260501234342.2518281-1-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. Fixes: 479e58549b0f ("crash_dump: store dm crypt keys in kdump reserved memory") Signed-off-by: Coiby Xu --- kernel/crash_dump_dm_crypt.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c index 4d8a3331bbe7..6377ee86ec50 100644 --- a/kernel/crash_dump_dm_crypt.c +++ b/kernel/crash_dump_dm_crypt.c @@ -429,6 +429,7 @@ int crash_load_dm_crypt_keys(struct kimage *image) }; int r = 0; + mutex_lock(&config_keys_subsys.su_mutex); if (key_count <= 0) { kexec_dprintk("No dm-crypt keys\n"); @@ -479,6 +480,9 @@ void kexec_file_post_load_cleanup_dm_crypt(struct kimage *image) kfree_sensitive(keys_header); keys_header = NULL; } + + if (mutex_is_locked(&config_keys_subsys.su_mutex)) + mutex_unlock(&config_keys_subsys.su_mutex); } static int __init configfs_dmcrypt_keys_init(void) -- 2.54.0