From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 68D3FD1039E for ; Fri, 25 Oct 2024 15:35:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=FqqZ87u1WPuZmS6TiBlypdGebi8AgQgWhtfy7RQxIyo=; b=xEbgUDsk7kXQXq dmReUhy2x2/QZJdgxUr0PjQ5U4OfBdokDYMVeuh6VcIjq0nJjoQPPk9LD5u4vxiWR+/Fzja8deMnW I8hiC7gyKo2APOxVO0jEQyv7/xsOZ7CNryw3j/2mjf+tZinYNtJCi837co18y+nahX8YCAlZHmFyg X1NZ0YV6sBW/A7FFhqWL7WniXUQIsanCXb5EFCOBmPBZeRIfEOdp2SsCNVnYzH9D0w+2Ei4yMB6qt DJC6olVrNCzDg/XdonCQeADYje4psqDxFDKKutXwSB7daseF/akfSYiEge3Yhft8Psk7K0mmekn6I abGJuP5N+XjfE0zpThow==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t4MLR-00000004GQw-3vFt; Fri, 25 Oct 2024 15:35:22 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t4Lz8-00000004Al2-2i6d for kexec@lists.infradead.org; Fri, 25 Oct 2024 15:12:20 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1729869136; 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: in-reply-to:in-reply-to:references:references; bh=RBGqG14Ir1TauPvJbSz3jQOA9+mQRgCc4BCTlJgnkuA=; b=LebQPXrfVL7RSUI6S2s+LGqKXscTgYneJrnx4c/I5q/gEVhCzhrdnbAhCOprfYv0ccMju+ r7CMfgXrdYWtyZQdbyET0Th/KkD0wvPNz2wvtqq6gnjp3aDMVS5PMPhSN9aGMVzdyl8A6U leZv7uzOou8K8J8wjH7uMCXy01ocINU= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-602-pkIUU_7mPiOuJegdS3U3rg-1; Fri, 25 Oct 2024 11:12:13 -0400 X-MC-Unique: pkIUU_7mPiOuJegdS3U3rg-1 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7C5211955F43; Fri, 25 Oct 2024 15:12:10 +0000 (UTC) Received: from t14s.redhat.com (unknown [10.22.65.27]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id AF463300018D; Fri, 25 Oct 2024 15:12:02 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-s390@vger.kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, kexec@lists.infradead.org, David Hildenbrand , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Baoquan He , Vivek Goyal , Dave Young , Thomas Huth , Cornelia Huck , Janosch Frank , Claudio Imbrenda , Eric Farman , Andrew Morton Subject: [PATCH v1 03/11] fs/proc/vmcore: disallow vmcore modifications after the vmcore was opened Date: Fri, 25 Oct 2024 17:11:25 +0200 Message-ID: <20241025151134.1275575-4-david@redhat.com> In-Reply-To: <20241025151134.1275575-1-david@redhat.com> References: <20241025151134.1275575-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241025_081218_803775_453DD710 X-CRM114-Status: GOOD ( 15.06 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org Let's protect all vmcore modifications by the vmcore_mutex and disallow vmcore modifications after the vmcore was opened: modifications would no longer be safe. Properly synchronize against concurrent opening of the vmcore. As a nice side-effect, we now properly protect concurrent vmcore modifications. No need to grab the mutex during mmap()/read(): after we opened the vmcore, modifications are impossible. Signed-off-by: David Hildenbrand --- fs/proc/vmcore.c | 42 +++++++++++++++++++----------------------- 1 file changed, 19 insertions(+), 23 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index b91c304463c9..6371dbaa21be 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -243,33 +243,27 @@ static int vmcoredd_copy_dumps(struct iov_iter *iter, u64 start, size_t size) { struct vmcoredd_node *dump; u64 offset = 0; - int ret = 0; size_t tsz; char *buf; - mutex_lock(&vmcore_mutex); list_for_each_entry(dump, &vmcoredd_list, list) { if (start < offset + dump->size) { tsz = min(offset + (u64)dump->size - start, (u64)size); buf = dump->buf + start - offset; - if (copy_to_iter(buf, tsz, iter) < tsz) { - ret = -EFAULT; - goto out_unlock; - } + if (copy_to_iter(buf, tsz, iter) < tsz) + return -EFAULT; size -= tsz; start += tsz; /* Leave now if buffer filled already */ if (!size) - goto out_unlock; + return 0; } offset += dump->size; } -out_unlock: - mutex_unlock(&vmcore_mutex); - return ret; + return 0; } #ifdef CONFIG_MMU @@ -278,20 +272,16 @@ static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst, { struct vmcoredd_node *dump; u64 offset = 0; - int ret = 0; size_t tsz; char *buf; - mutex_lock(&vmcore_mutex); list_for_each_entry(dump, &vmcoredd_list, list) { if (start < offset + dump->size) { tsz = min(offset + (u64)dump->size - start, (u64)size); buf = dump->buf + start - offset; if (remap_vmalloc_range_partial(vma, dst, buf, 0, - tsz)) { - ret = -EFAULT; - goto out_unlock; - } + tsz)) + return -EFAULT; size -= tsz; start += tsz; @@ -299,14 +289,12 @@ static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst, /* Leave now if buffer filled already */ if (!size) - goto out_unlock; + return 0; } offset += dump->size; } -out_unlock: - mutex_unlock(&vmcore_mutex); - return ret; + return 0; } #endif /* CONFIG_MMU */ #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */ @@ -1482,6 +1470,10 @@ int vmcore_add_device_dump(struct vmcoredd_data *data) return -EINVAL; } + /* We'll recheck under lock later. */ + if (data_race(vmcore_opened)) + return -EBUSY; + if (!data || !strlen(data->dump_name) || !data->vmcoredd_callback || !data->size) return -EINVAL; @@ -1515,12 +1507,16 @@ int vmcore_add_device_dump(struct vmcoredd_data *data) dump->buf = buf; dump->size = data_size; - /* Add the dump to driver sysfs list */ + /* Add the dump to driver sysfs list and update the elfcore hdr */ mutex_lock(&vmcore_mutex); - list_add_tail(&dump->list, &vmcoredd_list); - mutex_unlock(&vmcore_mutex); + if (vmcore_opened) { + ret = -EBUSY; + goto out_err; + } + list_add_tail(&dump->list, &vmcoredd_list); vmcoredd_update_size(data_size); + mutex_unlock(&vmcore_mutex); return 0; out_err: -- 2.46.1 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec