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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 8789FC433E0 for ; Wed, 17 Feb 2021 14:45:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 430F264E02 for ; Wed, 17 Feb 2021 14:45:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233602AbhBQOou (ORCPT ); Wed, 17 Feb 2021 09:44:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233598AbhBQOob (ORCPT ); Wed, 17 Feb 2021 09:44:31 -0500 Received: from mail-lf1-x12d.google.com (mail-lf1-x12d.google.com [IPv6:2a00:1450:4864:20::12d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0BF0BC061756 for ; Wed, 17 Feb 2021 06:43:51 -0800 (PST) Received: by mail-lf1-x12d.google.com with SMTP id d24so21844323lfs.8 for ; Wed, 17 Feb 2021 06:43:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=V8FxXuT4j8laMTP+nqfNAPzKKyyOeazfWCeXnGIadDA=; b=lOsoc9XKEvECRyePRX2tUvEu0JRzP5yzZBVXwuu/P7813LsNLMaHlHExbgC//l/5qL tob9oTtX8KZwJjeKeX4sWE7vOOYrbmb31cTSVxOWjRwsJQ1q5Gw26HaCyT2lglsVPGjR slv/MqdykBPyvB3t/3HtBWZ9/ldxnaQ6NH2tRIypJoemlO9qQ0xRW6RwidvkpszlpD4O CFPRH4y4HdmvsiclxX6PfcVYjonLAh4atIwMpsHd7HoFiexG55NbNQYKKqwW6jOwLU6r 7E6Kbd9Tv5dMrn0Odm2yLlXm9p+srcAaJMIje5z7cUr+O38mBqusRposBjveNxlj+CxT IAvQ== 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:subject:date:message-id:mime-version :content-transfer-encoding; bh=V8FxXuT4j8laMTP+nqfNAPzKKyyOeazfWCeXnGIadDA=; b=FwKhT42WPHR5lMChLraTJAJspTg0+9ts7CkGX8pI0XlNXARd/y6toQTuyjjUlkq/p3 nkXBrLXLBwZ5JPBIUYlZA2uTch7Wu22KZoM4vLZ1vZVNvB2y7o3fPDIuEltl2VwFHzRr mHFjmso47ESh5j/9i+LmvHVHxoSH9FxChh99hxqorajKpkbFjsJ+ZVutmVmhA2R6hoRk xEyq61wPhIeSoUP3YnHVx4t9CrStpQsznOgJuqWzAF8zwsni6b324glymNHUrs7xMEJg Q6kQm1QBiFy9iqDnCNQ0z7UpILS4AVIVXPyhLf/bHIDPq3uZyI6q8GKcmMefukkuS6DC 6ywQ== X-Gm-Message-State: AOAM530DyYAhNQ9tvidBS53jGveuYQO+7Wpz0sgapLX99FgVnzhb4KsZ dHxI65WEoPDj4dzeuX4hO8EDU0sfeva5RhjE X-Google-Smtp-Source: ABdhPJxKnuUhiwaiYroJRt6DhyFnnf/IYdPMC8G5xe761e2h9OkkiA2d42zDzhuVtRI9HQ66TitE/w== X-Received: by 2002:a19:c792:: with SMTP id x140mr15192729lff.546.1613573029440; Wed, 17 Feb 2021 06:43:49 -0800 (PST) Received: from localhost.localdomain ([146.158.65.225]) by smtp.googlemail.com with ESMTPSA id b28sm270522lfo.190.2021.02.17.06.43.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Feb 2021 06:43:48 -0800 (PST) From: Sabyrzhan Tasbolatov To: gregkh@linuxfoundation.org, jirislaby@kernel.org Cc: linux-kernel@vger.kernel.org, syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com Subject: [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write() Date: Wed, 17 Feb 2021 20:43:47 +0600 Message-Id: <20210217144347.2962551-1-snovitoll@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org syzbot found WARNING in iov_iter_revert[1] when iov_iter_count() returns 0, therefore INT_MAX is passed to iov_iter_revert() causing > MAX_RW_COUNT warning. static inline ssize_t do_tty_write() { .. size_t count = iov_iter_count(from); .. size_t size = count; if (ret != size) iov_iter_revert(from, size-ret); [1] WARNING: lib/iov_iter.c:1090 Call Trace: do_tty_write drivers/tty/tty_io.c:967 [inline] file_tty_write.constprop.0+0x55f/0x8f0 drivers/tty/tty_io.c:1048 call_write_iter include/linux/fs.h:1901 [inline] new_sync_write+0x426/0x650 fs/read_write.c:518 vfs_write+0x791/0xa30 fs/read_write.c:605 ksys_write+0x12d/0x250 fs/read_write.c:658 Fixes: 494e63ee9c("tty: implement write_iter") Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com Signed-off-by: Sabyrzhan Tasbolatov --- drivers/tty/tty_io.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 816e709afa56..8d6d579ecc3b 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -905,6 +905,9 @@ static inline ssize_t do_tty_write( ssize_t ret, written = 0; unsigned int chunk; + if (!count) + return -EINVAL; + ret = tty_write_lock(tty, file->f_flags & O_NDELAY); if (ret < 0) return ret; -- 2.25.1