From patchwork Sun Apr 10 20:58:46 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergei Trofimovich X-Patchwork-Id: 697001 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id p3AKuPTN013473 for ; Sun, 10 Apr 2011 20:56:25 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755138Ab1DJU4W (ORCPT ); Sun, 10 Apr 2011 16:56:22 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:37361 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754441Ab1DJU4V (ORCPT ); Sun, 10 Apr 2011 16:56:21 -0400 Received: by fxm17 with SMTP id 17so3203777fxm.19 for ; Sun, 10 Apr 2011 13:56:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:date:from:to:cc:subject:message-id:in-reply-to :references:x-mailer:mime-version:content-type; bh=kjULOVhQhEwS9D4FgmDMKtIs4pPrU/ffK3hMKPxnKh0=; b=Gr4kk7mAUKvtmnwp4qwlYIsalzyyd86Q9BLebHKtntf+A1J/rcSUOeYzBNZ/saxCe7 QRbL0mLUqQ3YQGtecsI1bUNw19IuRwcwO/3jwKTNqSiq3sU0kj+aALk5X2MRoO4pO4xh iq2voPhXY4LgKpfZCaFYJ3URvpXpi8UZ93AVE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:in-reply-to:references:x-mailer :mime-version:content-type; b=ForZlEEmMTHGpTYQLOYfRlmzT8scRIVxV2FowXs92b8UWzTKLzFu4lb8yPrcIteUud H2QEzkRBckH3dIxFg2gyCAGi96+YzXUamo3VJ71TWvocQMAcAxT32LGwp1GGl07EqH2R ZKnnQ+QoPd+tufrAzK4zneN4xBc1/KdUARNC0= Received: by 10.223.2.2 with SMTP id 2mr4631738fah.47.1302468980210; Sun, 10 Apr 2011 13:56:20 -0700 (PDT) Received: from sf ([178.125.152.109]) by mx.google.com with ESMTPS id o17sm1445292fal.1.2011.04.10.13.56.17 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 10 Apr 2011 13:56:19 -0700 (PDT) Date: Sun, 10 Apr 2011 23:58:46 +0300 From: Sergei Trofimovich To: Sergei Trofimovich Cc: chris.mason@oracle.com, linux-btrfs@vger.kernel.org, cwillu Subject: [PATCH v2] Re: btrfs does not work on usermode linux Message-ID: <20110410235846.135e801e@sf> In-Reply-To: <20110410232403.617c3b7f@sf> References: <20110410133710.0ef34cb6@sf> <20110410184249.483d8d67@sf> <20110410230622.09e965ae@sf> <20110410232403.617c3b7f@sf> X-Mailer: Claws Mail 3.7.8 (GTK+ 2.22.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Sun, 10 Apr 2011 20:56:25 +0000 (UTC) From 2ac9dd9cc54cee51c5c5219e35cca18a9f3f3a3f Mon Sep 17 00:00:00 2001 From: Sergei Trofimovich Date: Sun, 10 Apr 2011 23:19:53 +0300 Subject: [PATCH] btrfs: properly handle overlapping areas in memmove_extent_buffer MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fix data corruption caused by memcpy() usage on overlapping data. I've observed it first when found out usermode linux crash on btrfs. ?all chain is the following: ------------[ cut here ]------------ WARNING: at /home/slyfox/linux-2.6/fs/btrfs/extent_io.c:3900 memcpy_extent_buffer+0x1a5/0x219() Call Trace: 6fa39a58: [<601b495e>] _raw_spin_unlock_irqrestore+0x18/0x1c 6fa39a68: [<60029ad9>] warn_slowpath_common+0x59/0x70 6fa39aa8: [<60029b05>] warn_slowpath_null+0x15/0x17 6fa39ab8: [<600efc97>] memcpy_extent_buffer+0x1a5/0x219 6fa39b48: [<600efd9f>] memmove_extent_buffer+0x94/0x208 6fa39bc8: [<600becbf>] btrfs_del_items+0x214/0x473 6fa39c78: [<600ce1b0>] btrfs_delete_one_dir_name+0x7c/0xda 6fa39cc8: [<600dad6b>] __btrfs_unlink_inode+0xad/0x25d 6fa39d08: [<600d7864>] btrfs_start_transaction+0xe/0x10 6fa39d48: [<600dc9ff>] btrfs_unlink_inode+0x1b/0x3b 6fa39d78: [<600e04bc>] btrfs_unlink+0x70/0xef 6fa39dc8: [<6007f0d0>] vfs_unlink+0x58/0xa3 6fa39df8: [<60080278>] do_unlinkat+0xd4/0x162 6fa39e48: [<600517db>] call_rcu_sched+0xe/0x10 6fa39e58: [<600452a8>] __put_cred+0x58/0x5a 6fa39e78: [<6007446c>] sys_faccessat+0x154/0x166 6fa39ed8: [<60080317>] sys_unlink+0x11/0x13 6fa39ee8: [<60016b80>] handle_syscall+0x58/0x70 6fa39f08: [<60021377>] userspace+0x2d4/0x381 6fa39fc8: [<60014507>] fork_handler+0x62/0x69 ---[ end trace 70b0ca2ef0266b93 ]--- http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg09302.html Signed-off-by: Sergei Trofimovich --- fs/btrfs/extent_io.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 20ddb28..786a0f7 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3878,31 +3878,40 @@ static void move_pages(struct page *dst_page, struct page *src_page, char *s = src_kaddr + src_off + len; while (len--) *--p = *--s; kunmap_atomic(src_kaddr, KM_USER1); } kunmap_atomic(dst_kaddr, KM_USER0); } +static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len) +{ + unsigned long distance = (src > dst) ? src - dst : dst - src; + return distance < len; +} + static void copy_pages(struct page *dst_page, struct page *src_page, unsigned long dst_off, unsigned long src_off, unsigned long len) { char *dst_kaddr = kmap_atomic(dst_page, KM_USER0); char *src_kaddr; if (dst_page != src_page) src_kaddr = kmap_atomic(src_page, KM_USER1); else + { src_kaddr = dst_kaddr; + BUG_ON(areas_overlap(src_off, dst_off, len)); + } memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len); kunmap_atomic(dst_kaddr, KM_USER0); if (dst_page != src_page) kunmap_atomic(src_kaddr, KM_USER1); } void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { @@ -3963,21 +3972,21 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, if (src_offset + len > dst->len) { printk(KERN_ERR "btrfs memmove bogus src_offset %lu move " "len %lu len %lu\n", src_offset, len, dst->len); BUG_ON(1); } if (dst_offset + len > dst->len) { printk(KERN_ERR "btrfs memmove bogus dst_offset %lu move " "len %lu len %lu\n", dst_offset, len, dst->len); BUG_ON(1); } - if (dst_offset < src_offset) { + if (!areas_overlap(src_offset, dst_offset, len)) { memcpy_extent_buffer(dst, dst_offset, src_offset, len); return; } while (len > 0) { dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT; src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT; dst_off_in_page = (start_offset + dst_end) & ((unsigned long)PAGE_CACHE_SIZE - 1); src_off_in_page = (start_offset + src_end) & -- 1.7.3.4