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[2620:137:e000::1:20]) by mx.google.com with ESMTP id a21-20020a056a001d1500b00686f001cb5esi5474024pfx.319.2023.08.07.03.49.31; Mon, 07 Aug 2023 03:49:44 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linux.microsoft.com header.s=default header.b=l+M2Sgvx; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linux.microsoft.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229587AbjHGJwH (ORCPT + 99 others); Mon, 7 Aug 2023 05:52:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229998AbjHGJwE (ORCPT ); Mon, 7 Aug 2023 05:52:04 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C316D1BCD; Mon, 7 Aug 2023 02:51:44 -0700 (PDT) Received: from linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net (linux.microsoft.com [13.77.154.182]) by linux.microsoft.com (Postfix) with ESMTPSA id 4C043208694F; Mon, 7 Aug 2023 02:51:02 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 4C043208694F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1691401862; bh=I8JPvW2x4wvhQ88X64Egmr5ves+Y3CqToeE6x4H3cos=; h=From:To:Cc:Subject:Date:From; b=l+M2Sgvx6w0bgLv9XXrQoQ/gVH46rV69/VdKwlhKbdqKgMZ2A5+EXQ9B7lutxuq76 U9QQGAGv0/Mops1yLwpjZ2Pc4I69vqAwCV80g2KHbLkBh5ZLTCz0mx2WBAa/ONFa5D LYFVdF5MNiL8PMglP0jIoH2zNyyQIxz/KJ4WOIW0= From: Saurabh Sengar To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, ssengar@microsoft.com Subject: [PATCH] hv: hyperv.h: Replace one-element array with flexible-array member Date: Mon, 7 Aug 2023 02:50:53 -0700 Message-Id: <1691401853-26974-1-git-send-email-ssengar@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 X-Spam-Status: No, score=-19.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_MED, SPF_HELO_PASS,SPF_PASS,USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1773567092582984671 X-GMAIL-MSGID: 1773567092582984671 One-element and zero-length arrays are deprecated. Replace one-element array in struct vmtransfer_page_packet_header with flexible-array member. This change fixes below warning: [ 2.593788] ================================================================================ [ 2.593908] UBSAN: array-index-out-of-bounds in drivers/net/hyperv/netvsc.c:1445:41 [ 2.593989] index 1 is out of range for type 'vmtransfer_page_range [1]' [ 2.594049] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.5.0-rc4-next-20230803+ #1 [ 2.594114] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 04/20/2023 [ 2.594121] Call Trace: [ 2.594126] [ 2.594133] dump_stack_lvl+0x4c/0x70 [ 2.594154] dump_stack+0x14/0x20 [ 2.594162] __ubsan_handle_out_of_bounds+0xa6/0xf0 [ 2.594224] netvsc_poll+0xc01/0xc90 [hv_netvsc] [ 2.594258] __napi_poll+0x30/0x1e0 [ 2.594320] net_rx_action+0x194/0x2f0 [ 2.594333] __do_softirq+0xde/0x31e [ 2.594345] __irq_exit_rcu+0x6b/0x90 [ 2.594357] irq_exit_rcu+0x12/0x20 [ 2.594366] sysvec_hyperv_callback+0x84/0x90 [ 2.594376] [ 2.594379] [ 2.594383] asm_sysvec_hyperv_callback+0x1f/0x30 [ 2.594394] RIP: 0010:pv_native_safe_halt+0xf/0x20 [ 2.594452] Code: 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 05 35 3f 00 fb f4 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 [ 2.594459] RSP: 0018:ffffb841c00d3e88 EFLAGS: 00000256 [ 2.594469] RAX: ffff9d18c326f4a0 RBX: ffff9d18c031df40 RCX: 4000000000000000 [ 2.594475] RDX: 0000000000000001 RSI: 0000000000000082 RDI: 00000000000268dc [ 2.594481] RBP: ffffb841c00d3e90 R08: 00000066a171109b R09: 00000000d33d2600 [ 2.594486] R10: 000000009a41bf00 R11: 0000000000000000 R12: 0000000000000001 [ 2.594491] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 2.594501] ? ct_kernel_exit.constprop.0+0x7d/0x90 [ 2.594513] ? default_idle+0xd/0x20 [ 2.594523] arch_cpu_idle+0xd/0x20 [ 2.594532] default_idle_call+0x30/0xe0 [ 2.594542] do_idle+0x200/0x240 [ 2.594553] ? complete+0x71/0x80 [ 2.594613] cpu_startup_entry+0x24/0x30 [ 2.594624] start_secondary+0x12d/0x160 [ 2.594634] secondary_startup_64_no_verify+0x17e/0x18b [ 2.594649] [ 2.594656] ================================================================================ With this change the structure size is reduced by 8 bytes, below is the pahole output. struct vmtransfer_page_packet_header { struct vmpacket_descriptor d; /* 0 16 */ u16 xfer_pageset_id; /* 16 2 */ u8 sender_owns_set; /* 18 1 */ u8 reserved; /* 19 1 */ u32 range_cnt; /* 20 4 */ struct vmtransfer_page_range ranges[]; /* 24 0 */ /* size: 24, cachelines: 1, members: 6 */ /* last cacheline: 24 bytes */ }; Signed-off-by: Saurabh Sengar --- include/linux/hyperv.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index bfbc37ce223b..c529f407bfb8 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -348,7 +348,7 @@ struct vmtransfer_page_packet_header { u8 sender_owns_set; u8 reserved; u32 range_cnt; - struct vmtransfer_page_range ranges[1]; + struct vmtransfer_page_range ranges[]; } __packed; struct vmgpadl_packet_header {