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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD051C433E0 for ; Tue, 9 Mar 2021 11:25:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7334A65258 for ; Tue, 9 Mar 2021 11:25:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230035AbhCILYh (ORCPT ); Tue, 9 Mar 2021 06:24:37 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:13586 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229837AbhCILYF (ORCPT ); Tue, 9 Mar 2021 06:24:05 -0500 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4Dvt8m0WCHz16G9C; Tue, 9 Mar 2021 19:22:16 +0800 (CST) Received: from [10.174.177.143] (10.174.177.143) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.498.0; Tue, 9 Mar 2021 19:23:53 +0800 Subject: Re: [PATCH 5.12] io_uring: Convert personality_idr to XArray To: Pavel Begunkov , Jens Axboe , CC: Matthew Wilcox , Stefan Metzmacher , References: <7ccff36e1375f2b0ebf73d957f037b43becc0dde.1615212806.git.asml.silence@gmail.com> <803bad80-093a-5fbf-7677-754c9afad530@gmail.com> From: yangerkun Message-ID: <8b553635-b3d9-cb36-34f0-83777bec94ab@huawei.com> Date: Tue, 9 Mar 2021 19:23:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <803bad80-093a-5fbf-7677-754c9afad530@gmail.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.143] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 在 2021/3/8 22:22, Pavel Begunkov 写道: > On 08/03/2021 14:16, Pavel Begunkov wrote: >> From: "Matthew Wilcox (Oracle)" >> >> You can't call idr_remove() from within a idr_for_each() callback, >> but you can call xa_erase() from an xa_for_each() loop, so switch the >> entire personality_idr from the IDR to the XArray. This manifests as a >> use-after-free as idr_for_each() attempts to walk the rest of the node >> after removing the last entry from it. > > yangerkun, can you test it and similarly take care of buffer idr? Will try it latter :) > > >> >> Fixes: 071698e13ac6 ("io_uring: allow registering credentials") >> Cc: stable@vger.kernel.org # 5.6+ >> Reported-by: yangerkun >> Signed-off-by: Matthew Wilcox (Oracle) >> [Pavel: rebased (creds load was moved into io_init_req())] >> Signed-off-by: Pavel Begunkov >> --- >> fs/io_uring.c | 47 ++++++++++++++++++++++++----------------------- >> 1 file changed, 24 insertions(+), 23 deletions(-) >> >> p.s. passes liburing tests well >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index 5ef9f836cccc..5505e19f1391 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -407,7 +407,8 @@ struct io_ring_ctx { >> >> struct idr io_buffer_idr; >> >> - struct idr personality_idr; >> + struct xarray personalities; >> + u32 pers_next; >> >> struct { >> unsigned cached_cq_tail; >> @@ -1138,7 +1139,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) >> init_completion(&ctx->ref_comp); >> init_completion(&ctx->sq_thread_comp); >> idr_init(&ctx->io_buffer_idr); >> - idr_init(&ctx->personality_idr); >> + xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1); >> mutex_init(&ctx->uring_lock); >> init_waitqueue_head(&ctx->wait); >> spin_lock_init(&ctx->completion_lock); >> @@ -6338,7 +6339,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, >> req->work.list.next = NULL; >> personality = READ_ONCE(sqe->personality); >> if (personality) { >> - req->work.creds = idr_find(&ctx->personality_idr, personality); >> + req->work.creds = xa_load(&ctx->personalities, personality); >> if (!req->work.creds) >> return -EINVAL; >> get_cred(req->work.creds); >> @@ -8359,7 +8360,6 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx) >> mutex_unlock(&ctx->uring_lock); >> io_eventfd_unregister(ctx); >> io_destroy_buffers(ctx); >> - idr_destroy(&ctx->personality_idr); >> >> #if defined(CONFIG_UNIX) >> if (ctx->ring_sock) { >> @@ -8424,7 +8424,7 @@ static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id) >> { >> const struct cred *creds; >> >> - creds = idr_remove(&ctx->personality_idr, id); >> + creds = xa_erase(&ctx->personalities, id); >> if (creds) { >> put_cred(creds); >> return 0; >> @@ -8433,14 +8433,6 @@ static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id) >> return -EINVAL; >> } >> >> -static int io_remove_personalities(int id, void *p, void *data) >> -{ >> - struct io_ring_ctx *ctx = data; >> - >> - io_unregister_personality(ctx, id); >> - return 0; >> -} >> - >> static bool io_run_ctx_fallback(struct io_ring_ctx *ctx) >> { >> struct callback_head *work, *next; >> @@ -8530,13 +8522,17 @@ static void io_ring_exit_work(struct work_struct *work) >> >> static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) >> { >> + unsigned long index; >> + struct creds *creds; >> + >> mutex_lock(&ctx->uring_lock); >> percpu_ref_kill(&ctx->refs); >> /* if force is set, the ring is going away. always drop after that */ >> ctx->cq_overflow_flushed = 1; >> if (ctx->rings) >> __io_cqring_overflow_flush(ctx, true, NULL, NULL); >> - idr_for_each(&ctx->personality_idr, io_remove_personalities, ctx); >> + xa_for_each(&ctx->personalities, index, creds) >> + io_unregister_personality(ctx, index); >> mutex_unlock(&ctx->uring_lock); >> >> io_kill_timeouts(ctx, NULL, NULL); >> @@ -9166,10 +9162,9 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, >> } >> >> #ifdef CONFIG_PROC_FS >> -static int io_uring_show_cred(int id, void *p, void *data) >> +static int io_uring_show_cred(struct seq_file *m, unsigned int id, >> + const struct cred *cred) >> { >> - const struct cred *cred = p; >> - struct seq_file *m = data; >> struct user_namespace *uns = seq_user_ns(m); >> struct group_info *gi; >> kernel_cap_t cap; >> @@ -9237,9 +9232,13 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m) >> seq_printf(m, "%5u: 0x%llx/%u\n", i, buf->ubuf, >> (unsigned int) buf->len); >> } >> - if (has_lock && !idr_is_empty(&ctx->personality_idr)) { >> + if (has_lock && !xa_empty(&ctx->personalities)) { >> + unsigned long index; >> + const struct cred *cred; >> + >> seq_printf(m, "Personalities:\n"); >> - idr_for_each(&ctx->personality_idr, io_uring_show_cred, m); >> + xa_for_each(&ctx->personalities, index, cred) >> + io_uring_show_cred(m, index, cred); >> } >> seq_printf(m, "PollList:\n"); >> spin_lock_irq(&ctx->completion_lock); >> @@ -9568,14 +9567,16 @@ static int io_probe(struct io_ring_ctx *ctx, void __user *arg, unsigned nr_args) >> static int io_register_personality(struct io_ring_ctx *ctx) >> { >> const struct cred *creds; >> + u32 id; >> int ret; >> >> creds = get_current_cred(); >> >> - ret = idr_alloc_cyclic(&ctx->personality_idr, (void *) creds, 1, >> - USHRT_MAX, GFP_KERNEL); >> - if (ret < 0) >> - put_cred(creds); >> + ret = xa_alloc_cyclic(&ctx->personalities, &id, (void *)creds, >> + XA_LIMIT(0, USHRT_MAX), &ctx->pers_next, GFP_KERNEL); >> + if (!ret) >> + return id; >> + put_cred(creds); >> return ret; >> } >> >> >