From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 9DA4344C67C; Wed, 15 Jul 2026 12:29:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784118579; cv=none; b=pvkqBxmFjVnjQO9V4EGvnxxJ7NF/E/j1+K5L/3/9ATnnzZ8Vxah/yUB1TkkCbWp0YlO3/RLvVrjES18G+LjZZyrLx1v6M54lLGLDgF+UdTC/2XSmkpDT6EMIfVjrnv7AUEHwM28qUYGVtqWYpjEuX/msDpws0UpsusWb1yM88z8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784118579; c=relaxed/simple; bh=MUr9Gaaz4FUrLGgxoNJWXy2bynlshrKbu+RliG76WpE=; h=From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type:Date; b=IEHWHs0QyJL+ztR2gavGhJPVsYB395kYokqJJU0C2OIbdrWxtRcgH0nfdNY7o62bpZlx9FIQ2LDi90lwNhFgsWVWOhX3lrZW/ln5jfOjU1OT7PndJQGTVBhfZlzmjvhDr+Wiy9yKhZxBUXtVlhu/PKDoctL6fRaOTW4dOIew5PQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H4We6+xO; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="H4We6+xO" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id C119E1F00A3F; Wed, 15 Jul 2026 12:29:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784118575; bh=VxgyX43ll6PZid2/mZ07zFd4BnHMmz2/F+QfUAioERY=; h=From:To:Cc:Subject:Date; b=H4We6+xOP/LLuH6Khdub3AmojnFUuYx5bFyXZ1LWJuelmITg6UeLs+jXi5kKgqTD5 cqpX7i1rCVpleuCR//nVqFHSX223+jXyL2t+fdbL+XLl00stRlxGyf5+Btopew3VXd TuL0WpuLV24QLovnqulqH0KjCi7922vQr14kgIE3RZ455d4CtJgZu+LRSEY+lSLcGI YFL3UuQ0dCaDUDVebJanWCr54LmWz+/19FJyGZgdVxo5hTXCzJI9Ij9NRpuxA4/B7d 5fbrCDxiCwWJJtf01j1XYJZfQxXPlYkP6sqcEnMsu577aCes6ED6qIYkEwb+DSFeIA cewdqHxxPnoZQ== From: "syzbot" To: syzkaller-bugs@googlegroups.com, Slawomir Stepien , "Konstantin Komarov" , Cc: linux-kernel@vger.kernel.org, syzbot@lists.linux.dev, syzkaller-upstream-moderation@googlegroups.com Subject: [PATCH] fs/ntfs3: handle partial allocation in attr_data_get_block_locked() Message-ID: <8fc44517-e231-4539-a353-3dd47045a203@mail.kernel.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=UTF-8 Content-Transfer-Encoding: 8bit Date: Wed, 15 Jul 2026 12:29:34 +0000 (UTC) From: Slawomir Stepien When allocating clusters for a sparse or compressed attribute in attr_data_get_block_locked(), the requested virtual cluster number (vcn0) is aligned down to a frame boundary (vcn). The function then attempts to allocate a full frame of clusters. If the disk is nearly full and highly fragmented, attr_allocate_clusters() might only manage to allocate a small fragment and return success with a partial allocation length. If this partial allocation is so small that it does not even reach the originally requested vcn0 (i.e., end <= vcn0), vcn0 remains unallocated (a sparse hole). When the code subsequently calls run_lookup_entry() for vcn0, it finds the original SPARSE_LCN entry, which triggers a WARN_ON(1). Fix this by adding a check to verify if the partial allocation reached vcn0. If it did not (vcn0 >= end), treat this as an -ENOSPC failure and jump to the undo1 label. This safely rolls back the partial allocation, restores the original size, and repacks the runs, leaving the inode in a consistent state before returning the error to the caller. WARNING: fs/ntfs3/attrib.c:1236 at attr_data_get_block_locked+0x1980/0x25d0 fs/ntfs3/attrib.c:1236 RIP: 0010:attr_data_get_block_locked+0x1980/0x25d0 fs/ntfs3/attrib.c:1236 Call Trace: attr_data_get_block+0x1f1/0x2a0 fs/ntfs3/attrib.c:979 ntfs_fallocate+0xd3d/0xf70 fs/ntfs3/file.c:670 vfs_fallocate+0x663/0x7f0 fs/open.c:338 ksys_fallocate fs/open.c:362 [inline] __do_sys_fallocate fs/open.c:367 [inline] __se_sys_fallocate fs/open.c:365 [inline] __x64_sys_fallocate+0xbf/0x110 fs/open.c:365 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: 099ef9ab9203 ("fs/ntfs3: implement iomap-based file operations") Assisted-by: Gemini:gemini-3.1-pro-preview Gemini:gemini-3-flash-preview syzbot Reported-by: syzbot+7be6ad5cb228286af3e3@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7be6ad5cb228286af3e3 Link: https://syzkaller.appspot.com/ai_job?id=3c9dee6e-001d-4972-8bf6-f6c960708246 Signed-off-by: Slawomir Stepien --- diff --git a/fs/ntfs3/attrib.c b/fs/ntfs3/attrib.c index c621a4c58..786fd0ec0 100644 --- a/fs/ntfs3/attrib.c +++ b/fs/ntfs3/attrib.c @@ -1227,6 +1227,10 @@ int attr_data_get_block_locked(struct ntfs_inode *ni, CLST vcn, CLST clen, total_size = total_size0 + ((u64)*len << cluster_bits); if (vcn != vcn0) { + if (vcn0 >= end) { + err = -ENOSPC; + goto undo1; + } if (!run_lookup_entry(run, vcn0, lcn, len, NULL)) { err = -EINVAL; goto out; base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda -- See https://goo.gle/syzbot-ai-patches for information about AI-generated patches. You can comment on the patch as usual, syzbot will try to address the comments and send a new version of the patch if necessary. syzbot engineers can be reached at syzkaller@googlegroups.com.