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=-14.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 6FF0EC4320A for ; Sun, 1 Aug 2021 08:52:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A18861078 for ; Sun, 1 Aug 2021 08:52:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231598AbhHAIxD (ORCPT ); Sun, 1 Aug 2021 04:53:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229885AbhHAIxC (ORCPT ); Sun, 1 Aug 2021 04:53:02 -0400 Received: from mail-wm1-x332.google.com (mail-wm1-x332.google.com [IPv6:2a00:1450:4864:20::332]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 719DEC06175F; Sun, 1 Aug 2021 01:52:53 -0700 (PDT) Received: by mail-wm1-x332.google.com with SMTP id k4so8572801wms.3; Sun, 01 Aug 2021 01:52:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:references:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=3ntFFUEJHJ5MJEqHglVW9TCArN6M1xRMeieVLDZYfos=; b=hJ6JH0gCzDGS1MrnPCscTeCpmfb6Li55vIOs0sEBdTveTG2Kk/02VUBcTTD6LCUJMF +UUr3VU/2mMB8B+eEn0z1h4MSdlOo9aCNkBqBdpdDX2eX79iIK0B/V83DCz4exSjIQd9 XQxmU/99mG1c2fgMDHhqI5R9GpltCg9oRh4eBIeYu2HlXxczCAzOHWkKh26Zt1kKdsLP /SNcTJISpzJU2ky7S8JEFD4SbIBQmSIHVV8GHZ66JIi4m5Q0n729vseVzxzBO5VK3fdy 0rMw63VOQ50Xiw5WBuplDjO5EHTIFtWg9mdmDSx+Vey9I28Sad5fc5YVsGObieiOqHfY 0vGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:references:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=3ntFFUEJHJ5MJEqHglVW9TCArN6M1xRMeieVLDZYfos=; b=srd3xJpokqRfm7C9PZT756a+kOFM0Fl2bujAlYyLwWktGVbu6QGb3MNCBYaZadQ81B rg+tYvMsFoNVXlfNsEuRy0hUVALQr/aeZUa5VJBsp+LH2nyKhlsJQwnLBLZCBgx3R8W7 xp1eHQvL76zt1aF+H/oHHqwSU9QrLlCx1yv69bnpd6/pPoz0Kpn4HzkgrCgmaYeIeTpC y29om7OpxhcPM902Z58fYxm7c+OSVQYLWF6lYBO5hCTGv78iVAalQpVzvkJ2e8FEx1fl hfydr/KJaS6tvUHhCEk0C0IHKnp3+45XZmevNCPbHSRtMeYpBH63N3DwRYgse4YxOuz5 LtEw== X-Gm-Message-State: AOAM533NvI1lZhbmHWqJ3O4SRJQcIjXgrQhx45nH81IBo4ifjQ+qckrn tblo5Z6NWHM5kmktTuxqEclfRJ8UkCvBjg== X-Google-Smtp-Source: ABdhPJxryPAOk+H33xMnXFatjMlvm3y58+pkv8wvmLid4mLqFhosRp0QU/xr+yQD8nCYkHE+FxlmMw== X-Received: by 2002:a7b:c5c7:: with SMTP id n7mr11642922wmk.5.1627807971842; Sun, 01 Aug 2021 01:52:51 -0700 (PDT) Received: from [192.168.8.197] ([85.255.232.220]) by smtp.gmail.com with ESMTPSA id w18sm7673558wrg.68.2021.08.01.01.52.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 01 Aug 2021 01:52:51 -0700 (PDT) From: Pavel Begunkov To: Sudip Mukherjee , Jens Axboe Cc: io-uring@vger.kernel.org, linux-kernel References: Subject: Re: KASAN: stack-out-of-bounds in iov_iter_revert Message-ID: <4c339bea-87ff-cb41-732f-05fc5aff18fa@gmail.com> Date: Sun, 1 Aug 2021 09:52:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/1/21 1:10 AM, Pavel Begunkov wrote: > On 7/31/21 7:21 PM, Sudip Mukherjee wrote: >> Hi Jens, Pavel, >> >> We had been running syzkaller on v5.10.y and a "KASAN: >> stack-out-of-bounds in iov_iter_revert" was being reported on it. I >> got some time to check that today and have managed to get a syzkaller >> reproducer. I dont have a C reproducer which I can share but I can use >> the syz-reproducer to reproduce this with v5.14-rc3 and also with >> next-20210730. > > Can you try out the diff below? Not a full-fledged fix, but need to > check a hunch. > > If that's important, I was using this branch: > git://git.kernel.dk/linux-block io_uring-5.14 Or better this one, just in case it ooopses on warnings. diff --git a/fs/io_uring.c b/fs/io_uring.c index bf548af0426c..12284616854b 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3316,6 +3316,11 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags) /* no retry on NONBLOCK nor RWF_NOWAIT */ if (req->flags & REQ_F_NOWAIT) goto done; + if (iter->truncated) { + printk("truncated rd: %i\n", (int)iter->truncated); + iov_iter_reexpand(iter, iov_iter_count(iter) + iter->truncated); + iter->truncated = 0; + } /* some cases will consume bytes even on error returns */ iov_iter_revert(iter, io_size - iov_iter_count(iter)); ret = 0; @@ -3455,6 +3460,11 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags) kiocb_done(kiocb, ret2, issue_flags); } else { copy_iov: + if (iter->truncated) { + printk("truncated wr: %i\n", (int)iter->truncated); + iov_iter_reexpand(iter, iov_iter_count(iter) + iter->truncated); + iter->truncated = 0; + } /* some cases will consume bytes even on error returns */ iov_iter_revert(iter, io_size - iov_iter_count(iter)); ret = io_setup_async_rw(req, iovec, inline_vecs, iter, false); diff --git a/include/linux/uio.h b/include/linux/uio.h index 82c3c3e819e0..eff06d139fd4 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -30,6 +30,7 @@ enum iter_type { struct iov_iter { u8 iter_type; bool data_source; + u16 truncated; size_t iov_offset; size_t count; union { @@ -254,8 +255,10 @@ static inline void iov_iter_truncate(struct iov_iter *i, u64 count) * conversion in assignement is by definition greater than all * values of size_t, including old i->count. */ - if (i->count > count) + if (i->count > count) { + i->truncated += i->count - count; i->count = count; + } } /* @@ -264,6 +267,8 @@ static inline void iov_iter_truncate(struct iov_iter *i, u64 count) */ static inline void iov_iter_reexpand(struct iov_iter *i, size_t count) { + WARN_ON_ONCE(i->count > count); + i->truncated -= count - i->count; i->count = count; }