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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9EA07C61DA0 for ; Tue, 24 Jan 2023 13:45:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233908AbjAXNo7 (ORCPT ); Tue, 24 Jan 2023 08:44:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234304AbjAXNog (ORCPT ); Tue, 24 Jan 2023 08:44:36 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E996047420; Tue, 24 Jan 2023 05:43:21 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id F3A27B811D3; Tue, 24 Jan 2023 13:43:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6A56C433D2; Tue, 24 Jan 2023 13:43:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674567796; bh=rABEJ5R54kDbYVYt0oHBixOG5wLExHEGnQML3AO2kk4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ERU+UFS3D4KUAuwhK0AAvlqS5VZ1cE6Q4Z8+gqJm2HRvGh6oZzsXI58QoNj0aUG3m ToovmtMZTxtO6pmy7n5e+g//4emaoY1uLuB7KbS7jImYXlejq+6ICKVnH/o5OUX8Jd YMG4x4mIozAmfP06DIUl5xMPrnX+AP1ELAK6HF+z2qKlWLZsi5MxzFmZKe/uQoF43Z z290rOexIQy74wtk1oBlIWQTZol+Tq+qeV/kODPLck+4LjB1WRBaPK5R0+D+oBGnEK ivzhM4jTFxbp4bOvNVvFGcRFMiVDynNzHx6C+0oz2lSPozFIsyqcnsH0ljE62BJzRt EjTkpJniCeLwQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Siddh Raman Pant , syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com, Gao Xiang , Chao Yu , Sasha Levin , xiang@kernel.org, linux-erofs@lists.ozlabs.org Subject: [PATCH AUTOSEL 5.15 07/14] erofs/zmap.c: Fix incorrect offset calculation Date: Tue, 24 Jan 2023 08:42:50 -0500 Message-Id: <20230124134257.637523-7-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230124134257.637523-1-sashal@kernel.org> References: <20230124134257.637523-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Siddh Raman Pant [ Upstream commit 6acd87d50998ef0afafc441613aeaf5a8f5c9eff ] Effective offset to add to length was being incorrectly calculated, which resulted in iomap->length being set to 0, triggering a WARN_ON in iomap_iter_done(). Fix that, and describe it in comments. This was reported as a crash by syzbot under an issue about a warning encountered in iomap_iter_done(), but unrelated to erofs. C reproducer: https://syzkaller.appspot.com/text?tag=ReproC&x=1037a6b2880000 Kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=e2021a61197ebe02 Dashboard link: https://syzkaller.appspot.com/bug?extid=a8e049cd3abd342936b6 Reported-by: syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com Suggested-by: Gao Xiang Signed-off-by: Siddh Raman Pant Reviewed-by: Gao Xiang Reviewed-by: Chao Yu Link: https://lore.kernel.org/r/20221209102151.311049-1-code@siddh.me Signed-off-by: Gao Xiang Signed-off-by: Sasha Levin --- fs/erofs/zmap.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index 7a6df35fdc91..73b86b5c1a75 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -700,12 +700,16 @@ static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset, iomap->type = IOMAP_HOLE; iomap->addr = IOMAP_NULL_ADDR; /* - * No strict rule how to describe extents for post EOF, yet - * we need do like below. Otherwise, iomap itself will get + * No strict rule on how to describe extents for post EOF, yet + * we need to do like below. Otherwise, iomap itself will get * into an endless loop on post EOF. + * + * Calculate the effective offset by subtracting extent start + * (map.m_la) from the requested offset, and add it to length. + * (NB: offset >= map.m_la always) */ if (iomap->offset >= inode->i_size) - iomap->length = length + map.m_la - offset; + iomap->length = length + offset - map.m_la; } iomap->flags = 0; return 0; -- 2.39.0