From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7BD182C1B4; Sun, 1 Sep 2024 16:19:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725207560; cv=none; b=OQ3ye5V7wInDzYGkOoCQVwOqmTgW/ugNg7AYQMbj1AaLj4k5dO4XBbwzb75dYyH96fk6WqDcLE79SH93x320vq1hZ4YuHtaXNKZK11VeZ+V6brvxsW1qBU3S1MUfVzOYIZCLDAm2n7uvq5G0vpWYOiO+LbzAYBmG7Kk458mk9/w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725207560; c=relaxed/simple; bh=naerpwW5HIKun4xuIs2nqh1PQfPf51TAEzehaL0zlv0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hS7wMoi6TZYFz1rnujnJhfeAHV1CdP8bNIdmNkVpkVt7tKhq0Yyuxo7Amy17HWkouK61P8sHHXH9KOE9x2iNEEONlmJ7NLS6sJ68t/3HwX1o98jnV8i2M2s4rqf4iRyNxtAnxyXWt8juXIua66QN6AvEiiw8XYKxbVzaatJ3nbg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RRLErB4O; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RRLErB4O" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FE28C4CEC3; Sun, 1 Sep 2024 16:19:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725207560; bh=naerpwW5HIKun4xuIs2nqh1PQfPf51TAEzehaL0zlv0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RRLErB4ODQNh8ZYdoXX4e8/5ZG7f0sGlSuY6dzxnXoHGpQZAiJfVp+TqBsjmZGvGR fG4pKeN4FYcc2UErARlZqIcORNg+YpixsrvAStm8glcgd0iUl28U4RJjjLURNH0tAl aHURDxlNYRuGvqLW0KCbaGD71loJyZ76WQIcFiG8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, Jann Horn , Linus Torvalds Subject: [PATCH 4.19 01/98] fuse: Initialize beyond-EOF page contents before setting uptodate Date: Sun, 1 Sep 2024 18:15:31 +0200 Message-ID: <20240901160803.731972566@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240901160803.673617007@linuxfoundation.org> References: <20240901160803.673617007@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit 3c0da3d163eb32f1f91891efaade027fa9b245b9 upstream. fuse_notify_store(), unlike fuse_do_readpage(), does not enable page zeroing (because it can be used to change partial page contents). So fuse_notify_store() must be more careful to fully initialize page contents (including parts of the page that are beyond end-of-file) before marking the page uptodate. The current code can leave beyond-EOF page contents uninitialized, which makes these uninitialized page contents visible to userspace via mmap(). This is an information leak, but only affects systems which do not enable init-on-alloc (via CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y or the corresponding kernel command line parameter). Link: https://bugs.chromium.org/p/project-zero/issues/detail?id=2574 Cc: stable@kernel.org Fixes: a1d75f258230 ("fuse: add store request") Signed-off-by: Jann Horn Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/fuse/dev.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1671,9 +1671,11 @@ static int fuse_notify_store(struct fuse this_num = min_t(unsigned, num, PAGE_SIZE - offset); err = fuse_copy_page(cs, &page, offset, this_num, 0); - if (!err && offset == 0 && - (this_num == PAGE_SIZE || file_size == end)) + if (!PageUptodate(page) && !err && offset == 0 && + (this_num == PAGE_SIZE || file_size == end)) { + zero_user_segment(page, this_num, PAGE_SIZE); SetPageUptodate(page); + } unlock_page(page); put_page(page);