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 BC03D21D3C7 for ; Thu, 8 May 2025 07:12:41 +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=1746688364; cv=none; b=SZNS42D7tnDSVsDSedwABs2iJO8AuJlKfafNydXJvRf6h6xYHMzaEMSIFSUMAgMhMvrgv2sh4wrv5QbbmMF+6jGCEkjU8JDRU2oN4EblExqYtpTB/WRfZAL9504KoRp4o9XYThqHMjNEd4SjOoaCoe/t6dGyRzUAzN55XjxYhRE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746688364; c=relaxed/simple; bh=AWgzn73NCvxEyCgN4gP0yTSrKWx71kyIB/sVjnvnIE0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dvwNCSEmMUwUsayj3uGqSrq+fjdyHRvP3A5fUTRRBlliLNnr0n6XWoddWnAv7Rat26ZQwCuYNWLdsKDnszeI4Y/cy85pCh+iJFF2K5XFn1z6uWjZ5F0GMSHTPuG4LTB0K3AOFqM/zhNrmpxZF3L3bDp49mnF2WQ2ckCZhXJ9XN0= 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=FgfxTNj0; 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="FgfxTNj0" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1746688360; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TZTevEtSixkUFIWAAgpBtf54+V/8lG/q2RrDnXwunY8=; b=FgfxTNj0lY0+ZfH9Y9jzw47HW4pxxMJl8kc2VKNcupDeTDEcCvM8zNMP+kKxV4uL1QQwBN fIQ+9fp7okvH6GIakeDQi+hbXxjH8alXmWnp/JM2JdiP0yMARpASewQpfbtbeO6wCpphNY MpRHOBVskB8zzrzGcBksoF0P/wMmqA8= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-349-1vAZ0qsDO4-R41t-xROHMg-1; Thu, 08 May 2025 03:12:37 -0400 X-MC-Unique: 1vAZ0qsDO4-R41t-xROHMg-1 X-Mimecast-MFC-AGG-ID: 1vAZ0qsDO4-R41t-xROHMg_1746688356 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7ED751800370; Thu, 8 May 2025 07:12:35 +0000 (UTC) Received: from localhost (unknown [10.72.112.8]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 060A51953B85; Thu, 8 May 2025 07:12:32 +0000 (UTC) Date: Thu, 8 May 2025 15:12:28 +0800 From: Baoquan He To: Andrew Morton Cc: Coiby Xu , fuqiang wang , Vivek Goyal , Dave Young , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v4] x86/kexec: fix potential cmem->ranges out of bounds Message-ID: References: <20240108130720.228478-1-fuqiang.wang@easystack.cn> <4de3c2onosr7negqnfhekm4cpbklzmsimgdfv33c52dktqpza5@z5pb34ghz4at> <20250507225959.174dd1eed6b0b1354c95a0fd@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250507225959.174dd1eed6b0b1354c95a0fd@linux-foundation.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 On 05/07/25 at 10:59pm, Andrew Morton wrote: > On Thu, 8 May 2025 12:25:15 +0800 Coiby Xu wrote: > > > > > > >Acked-by: Baoquan He > > > > Hi Andrew, > > > > It seems this patch was missed. > > January 2024. Yes, it's fair to assume that it was missed ;) > > > Will you pick it up? > > Sure. > > > Without this patch, > > kdump kernel will fail to be loaded by the kexec_file_load, > > > > [ 139.736948] UBSAN: array-index-out-of-bounds in arch/x86/kernel/crash.c:350:25 > > [ 139.742360] index 0 is out of range for type 'range [*]' > > [ 139.745695] CPU: 0 UID: 0 PID: 5778 Comm: kexec Not tainted 6.15.0-0.rc3.20250425git02ddfb981de8.32.fc43.x86_64 #1 PREEMPT(lazy) > > [ 139.745698] Hardware name: Amazon EC2 c5.large/, BIOS 1.0 10/16/2017 > > [ 139.745699] Call Trace: > > [ 139.745700] > > [ 139.745701] dump_stack_lvl+0x5d/0x80 > > [ 139.745706] ubsan_epilogue+0x5/0x2b > > [ 139.745709] __ubsan_handle_out_of_bounds.cold+0x54/0x59 > > [ 139.745711] crash_setup_memmap_entries+0x2d9/0x330 > > [ 139.745716] setup_boot_parameters+0xf8/0x6a0 > > [ 139.745720] bzImage64_load+0x41b/0x4e0 > > [ 139.745722] ? find_next_iomem_res+0x109/0x140 > > [ 139.745727] ? locate_mem_hole_callback+0x109/0x170 > > [ 139.745737] kimage_file_alloc_init+0x1ef/0x3e0 > > [ 139.745740] __do_sys_kexec_file_load+0x180/0x2f0 > > [ 139.745742] do_syscall_64+0x7b/0x160 > > [ 139.745745] ? do_user_addr_fault+0x21a/0x690 > > [ 139.745747] ? exc_page_fault+0x7e/0x1a0 > > [ 139.745749] entry_SYSCALL_64_after_hwframe+0x76/0x7e > > [ 139.745751] RIP: 0033:0x7f7712c84e4d > > > > Do we know why this has appeared at such a late date? The reporter > must be doing something rare. > > Baoquan, please re-review this? > > A -stable backport is clearly required. A Fixes: would be nice, but I > assume this goes back a long time so it isn't worth spending a lot of > time working out when this was introduced. No need for stable kernel. The UBSAN only warns a potential risk, it won't happen in reality. I am talking to Coiby, he got it wrong about the testing result. He saw the UBSAN warning when UBSAN is enabled, while vmcore is till saved successfully. > > The patch needed a bit of work to apply to current code. I did the > below. It compiles. > > --- a/arch/x86/kernel/crash.c~x86-kexec-fix-potential-cmem-ranges-out-of-bounds > +++ a/arch/x86/kernel/crash.c > @@ -165,8 +165,18 @@ static struct crash_mem *fill_up_crash_e > /* > * Exclusion of crash region and/or crashk_low_res may cause > * another range split. So add extra two slots here. > + * > + * Exclusion of low 1M may not cause another range split, because the > + * range of exclude is [0, 1M] and the condition for splitting a new > + * region is that the start, end parameters are both in a certain > + * existing region in cmem and cannot be equal to existing region's > + * start or end. Obviously, the start of [0, 1M] cannot meet this > + * condition. > + * > + * But in order to lest the low 1M could be changed in the future, > + * (e.g. [stare, 1M]), add a extra slot. > */ > - nr_ranges += 2; > + nr_ranges += 3; > cmem = vzalloc(struct_size(cmem, ranges, nr_ranges)); > if (!cmem) > return NULL; > @@ -317,9 +327,16 @@ int crash_setup_memmap_entries(struct ki > * split. So use two slots here. > */ > nr_ranges = 2; > - cmem = vzalloc(struct_size(cmem, ranges, nr_ranges)); > + /* > + * In the current x86 architecture code, the elfheader is always > + * allocated at crashk_res.start. But it depends on the allocation > + * position of elfheader in crashk_res. To avoid potential out of > + * bounds in future, add a extra slot. > + */ > + cmem = vzalloc(struct_size(cmem, ranges, 2)); > if (!cmem) > return -ENOMEM; > + cmem->max_nr_ranges = 2; > > cmem->max_nr_ranges = nr_ranges; > cmem->nr_ranges = 0; > _ >