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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 6048DC433E2 for ; Tue, 23 Jun 2020 21:24:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C58B20724 for ; Tue, 23 Jun 2020 21:24:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592947482; bh=oSKrPkaQYSUPRUz11wt1xUB5OW2zFZ2Q4Hqjmvr8v3o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0EUKGSq4pHxSx2DQdeF12ULb5aToKudKFyeowiDdukO1NS2Ku5563SJmtaqqlG9BQ 4ydmk7vlDxY5jyn6u0wReQsabfmX2cS7j2CBMBbkQ4poqBQU27alHiQNTPq59ark/D jeh7U438mbHFf15/t5yHMUm97xIhUf7zMX6nZuX0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392611AbgFWVYl (ORCPT ); Tue, 23 Jun 2020 17:24:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:36632 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387792AbgFWUTa (ORCPT ); Tue, 23 Jun 2020 16:19:30 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AC7662073E; Tue, 23 Jun 2020 20:19:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592943570; bh=oSKrPkaQYSUPRUz11wt1xUB5OW2zFZ2Q4Hqjmvr8v3o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qK/JpdL3Rb67Eu0z7FMHh+PuWhbLtZvz7RiuyZucw0hcGfEIvWIqXZA0DaxDJ6XWe uHZ4hM+q4zTB0aTLKRMjIQQBRk63rJCQBn8vj4AkVeILOX8m+xzDzuqb1gY75IbxHA n2JpsmIFr6ApBAPZRHEgsZgNttQBuYXCD/QiuN3g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chris Wilson , Matthew Auld , Tvrtko Ursulin , Maciej Patelczyk , Joonas Lahtinen Subject: [PATCH 5.7 444/477] drm/i915/gem: Avoid iterating an empty list Date: Tue, 23 Jun 2020 21:57:21 +0200 Message-Id: <20200623195428.519257908@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200623195407.572062007@linuxfoundation.org> References: <20200623195407.572062007@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chris Wilson commit 757a9395f33c51c4e6eff2c7c0fbd50226a58224 upstream. Our __sgt_iter assumes that the scattergather list has at least one element. But during construction we may fail in allocating the first page, and so mark the first element as the terminator. This is unexpected! [22555.524752] RIP: 0010:shmem_get_pages+0x506/0x710 [i915] [22555.524759] Code: 49 8b 2c 24 31 c0 66 89 44 24 40 48 85 ed 0f 84 62 01 00 00 4c 8b 75 00 8b 5d 08 44 8b 7d 0c 48 8b 0d 7e 34 07 e2 49 83 e6 fc <49> 8b 16 41 01 df 48 89 cf 48 89 d0 48 c1 e8 2d 48 85 c9 0f 84 c8 [22555.524765] RSP: 0018:ffffc9000053f9d0 EFLAGS: 00010246 [22555.524770] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8881ffffa000 [22555.524774] RDX: fffffffffffffff4 RSI: ffffffffffffffff RDI: ffffffff821efe00 [22555.524778] RBP: ffff8881b099ab00 R08: 0000000000000000 R09: 00000000fffffff4 [22555.524782] R10: 0000000000000002 R11: 00000000ffec0a02 R12: ffff8881cd3c8d60 [22555.524786] R13: 00000000fffffff4 R14: 0000000000000000 R15: 0000000000000000 [22555.524790] FS: 00007f4fbeb9b9c0(0000) GS:ffff8881f8580000(0000) knlGS:0000000000000000 [22555.524795] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [22555.524799] CR2: 0000000000000000 CR3: 00000001ec7f0004 CR4: 00000000001606e0 [22555.524803] Call Trace: [22555.524919] __i915_gem_object_get_pages+0x4f/0x60 [i915] Fixes: 85d1225ec066 ("drm/i915: Introduce & use new lightweight SGL iterators") Signed-off-by: Chris Wilson Cc: Matthew Auld Cc: Tvrtko Ursulin Cc: # v4.8+ Reviewed-by: Matthew Auld Reviewed-by: Maciej Patelczyk Link: https://patchwork.freedesktop.org/patch/msgid/20200522132706.5133-1-chris@chris-wilson.co.uk (cherry picked from commit 957ad9a02be6faa87594c58ac09460cd3d190d0e) Signed-off-by: Joonas Lahtinen Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -39,7 +39,6 @@ static int shmem_get_pages(struct drm_i9 unsigned long last_pfn = 0; /* suppress gcc warning */ unsigned int max_segment = i915_sg_segment_size(); unsigned int sg_page_sizes; - struct pagevec pvec; gfp_t noreclaim; int ret; @@ -192,13 +191,17 @@ err_sg: sg_mark_end(sg); err_pages: mapping_clear_unevictable(mapping); - pagevec_init(&pvec); - for_each_sgt_page(page, sgt_iter, st) { - if (!pagevec_add(&pvec, page)) + if (sg != st->sgl) { + struct pagevec pvec; + + pagevec_init(&pvec); + for_each_sgt_page(page, sgt_iter, st) { + if (!pagevec_add(&pvec, page)) + check_release_pagevec(&pvec); + } + if (pagevec_count(&pvec)) check_release_pagevec(&pvec); } - if (pagevec_count(&pvec)) - check_release_pagevec(&pvec); sg_free_table(st); kfree(st);