From patchwork Fri Apr 18 09:38:23 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 14057111 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 D65121E2007; Fri, 18 Apr 2025 09:45:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744969539; cv=none; b=AArPcT3PPsWOjSHEZKYbiwRe9/+b1rp2oAzU61ah1CjC3mBULrt0ubLRSXVRUpdP3FpqxWSbg1E/p2HhmOYWWIWSg/HGygMZ9HqIUfywcRFKYfZfpP+9o19QHVka/FAv1GopfuklIcgmeq0+gLp/0VCw+ud74SbSHi3uNokTS5U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744969539; c=relaxed/simple; bh=CoasF90lxrVxf/2zxueq4tsA/XQ/Fum79XSA0kCbV1A=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=YtUrmXnlzOyG33S8pr65yqmuQ9bUTPT3VVGKSvzGgUaP3417uYIRn5KxVOo8l2abLW489jl2H4M4DvwoxJafe5YuqIGzQdQkG11azZSFYyiJ5WSygRiIv7uPYRCqPybJ987HE7hEtKWuIf0EwwgCoF5sDnMiMY950QY08ScABaU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Zf8y33DFHz4f3jtW; Fri, 18 Apr 2025 17:45:15 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id D98981A058E; Fri, 18 Apr 2025 17:45:33 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgBHrGA6HwJozQ1aJw--.29179S6; Fri, 18 Apr 2025 17:45:33 +0800 (CST) From: Yu Kuai To: axboe@kernel.dk, kbusch@kernel.org Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH 2/5] brd: synchronize using page and free page with rcu Date: Fri, 18 Apr 2025 17:38:23 +0800 Message-Id: <20250418093826.3149293-3-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20250418093826.3149293-1-yukuai1@huaweicloud.com> References: <20250418093826.3149293-1-yukuai1@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: gCh0CgBHrGA6HwJozQ1aJw--.29179S6 X-Coremail-Antispam: 1UD129KBjvJXoW7Kr4xtF4fJw1kXF45tr4xWFg_yoW8CF18pF 4UJ34xArZ8Cr4ay3WUX3Z0vFyrX3s7Gay8Gayxu3y5Kw4fGr9Fya48ta4Sqa45GryrCrW3 Zan0y3y8A34rCwUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBC14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jryl82xGYIkIc2 x26xkF7I0E14v26r4j6ryUM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY1x0262kKe7AKxVWUtVW8Zw CF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j 6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64 vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_ Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r4j6F4UMIIF0x vEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuYvjfU8yCGUUUUU X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ From: Yu Kuai Currently, after fetching the page by xa_load() in IO path, there is no protection and page can be freed concurrently by discard: cpu0 brd_submit_bio brd_do_bvec page = brd_lookup_page cpu1 brd_submit_bio brd_do_discard page = __xa_erase() __free_page() // page UAF Fix the problem by protecting page with rcu. Fixes: 9ead7efc6f3f ("brd: implement discard support") Signed-off-by: Yu Kuai --- drivers/block/brd.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index a6e4f005cb76..740ed13faaff 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -208,6 +208,7 @@ static int brd_do_bvec(struct brd_device *brd, struct page *page, goto out; } + rcu_read_lock(); mem = kmap_local_page(page); if (!op_is_write(opf)) { copy_from_brd(mem + off, brd, sector, len); @@ -217,11 +218,19 @@ static int brd_do_bvec(struct brd_device *brd, struct page *page, copy_to_brd(brd, mem + off, sector, len); } kunmap_local(mem); + rcu_read_unlock(); out: return err; } +static void brd_free_one_page(struct rcu_head *head) +{ + struct page *page = container_of(head, struct page, rcu_head); + + __free_page(page); +} + static void brd_do_discard(struct brd_device *brd, sector_t sector, u32 size) { sector_t aligned_sector = (sector + PAGE_SECTORS) & ~PAGE_SECTORS; @@ -232,7 +241,7 @@ static void brd_do_discard(struct brd_device *brd, sector_t sector, u32 size) while (size >= PAGE_SIZE && aligned_sector < rd_size * 2) { page = __xa_erase(&brd->brd_pages, aligned_sector >> PAGE_SECTORS_SHIFT); if (page) { - __free_page(page); + call_rcu(&page->rcu_head, brd_free_one_page); brd->brd_nr_pages--; } aligned_sector += PAGE_SECTORS;