From patchwork Mon Jun 3 13:44:32 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Sterba X-Patchwork-Id: 10972911 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6A74B6C5 for ; Mon, 3 Jun 2019 13:44:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5BBBF28833 for ; Mon, 3 Jun 2019 13:44:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4FEE928857; Mon, 3 Jun 2019 13:44:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CCB59287E7 for ; Mon, 3 Jun 2019 13:44:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728357AbfFCNoA (ORCPT ); Mon, 3 Jun 2019 09:44:00 -0400 Received: from mx2.suse.de ([195.135.220.15]:45178 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728226AbfFCNoA (ORCPT ); Mon, 3 Jun 2019 09:44:00 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2571DAF0F; Mon, 3 Jun 2019 13:43:59 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 2DE08DA85E; Mon, 3 Jun 2019 15:44:49 +0200 (CEST) From: David Sterba To: viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, David Sterba Subject: [PATCH] fs: use UB-safe check for signed addition overflow in remap_verify_area Date: Mon, 3 Jun 2019 15:44:32 +0200 Message-Id: <20190603134432.32156-1-dsterba@suse.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The following warning pops up with enabled UBSAN in tests fstests/generic/303: [23127.529395] UBSAN: Undefined behaviour in fs/read_write.c:1725:7 [23127.529400] signed integer overflow: [23127.529403] 4611686018427322368 + 9223372036854775807 cannot be represented in type 'long long int' [23127.529412] CPU: 4 PID: 26180 Comm: xfs_io Not tainted 5.2.0-rc2-1.ge195904-vanilla+ #450 [23127.556999] Hardware name: empty empty/S3993, BIOS PAQEX0-3 02/24/2008 [23127.557001] Call Trace: [23127.557060] dump_stack+0x67/0x9b [23127.557070] ubsan_epilogue+0x9/0x40 [23127.573496] handle_overflow+0xb3/0xc0 [23127.573514] do_clone_file_range+0x28f/0x2a0 [23127.573547] vfs_clone_file_range+0x35/0xb0 [23127.573564] ioctl_file_clone+0x8d/0xc0 [23127.590144] do_vfs_ioctl+0x300/0x700 [23127.590160] ksys_ioctl+0x70/0x80 [23127.590203] ? trace_hardirqs_off_thunk+0x1a/0x1c [23127.590210] __x64_sys_ioctl+0x16/0x20 [23127.590215] do_syscall_64+0x5c/0x1d0 [23127.590224] entry_SYSCALL_64_after_hwframe+0x49/0xbe [23127.590231] RIP: 0033:0x7ff6d7250327 [23127.590241] RSP: 002b:00007ffe3a38f1d8 EFLAGS: 00000206 ORIG_RAX: 0000000000000010 [23127.590246] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007ff6d7250327 [23127.590249] RDX: 00007ffe3a38f220 RSI: 000000004020940d RDI: 0000000000000003 [23127.590252] RBP: 0000000000000000 R08: 00007ffe3a3c80a0 R09: 00007ffe3a3c8080 [23127.590255] R10: 000000000fa99fa0 R11: 0000000000000206 R12: 0000000000000000 [23127.590260] R13: 0000000000000000 R14: 3fffffffffff0000 R15: 00007ff6d750a20c As loff_t is a signed type, we should use the safe overflow checks instead of relying on compiler implementation. The bogus values are intentional and the test is supposed to verify the boundary conditions. Signed-off-by: David Sterba --- fs/read_write.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/read_write.c b/fs/read_write.c index c543d965e288..a8bd974edf72 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "internal.h" #include @@ -1718,11 +1719,12 @@ static int remap_verify_area(struct file *file, loff_t pos, loff_t len, bool write) { struct inode *inode = file_inode(file); + loff_t tmp; if (unlikely(pos < 0 || len < 0)) return -EINVAL; - if (unlikely((loff_t) (pos + len) < 0)) + if (unlikely(check_add_overflow(pos, len, &tmp))) return -EINVAL; if (unlikely(inode->i_flctx && mandatory_lock(inode))) {