From nobody Sat Nov 15 05:39:10 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1755171563112530.8636638311108; Thu, 14 Aug 2025 04:39:23 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1umWI4-0002si-D4; Thu, 14 Aug 2025 07:38:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1umWHq-0002qH-Mv for qemu-devel@nongnu.org; Thu, 14 Aug 2025 07:38:27 -0400 Received: from air.basealt.ru ([193.43.8.18]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1umWHk-0000wV-5P for qemu-devel@nongnu.org; Thu, 14 Aug 2025 07:38:26 -0400 Received: from boringlust.malta.altlinux.ru (obninsk.basealt.ru [217.15.195.17]) (Authenticated sender: rastyoginds) by air.basealt.ru (Postfix) with ESMTPSA id 47386233B3; Thu, 14 Aug 2025 14:38:14 +0300 (MSK) From: gerben@altlinux.org To: qemu-devel@nongnu.org, richard.henderson@linaro.org, alex.bennee@linaro.org Cc: sdl.qemu@linuxtesting.org Subject: [PATCH] util/qht: fix possible NULL pointer dereference in qht_bucket_remove_entry() Date: Thu, 14 Aug 2025 14:37:40 +0300 Message-ID: <20250814113807.16146-1-gerben@altlinux.org> X-Mailer: git-send-email 2.42.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=193.43.8.18; envelope-from=gerben@altlinux.org; helo=air.basealt.ru X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1755171563934116600 Content-Type: text/plain; charset="utf-8" From: Denis Rastyogin If b->pointers[i] is NULL on the first iteration and prev has not yet been assigned (i.e., is still NULL), calling qht_entry_move(orig, pos, prev, QHT_BUCKET_ENTRIES - 1) can lead to a NULL pointer dereference. The qht_debug_assert(prev) check does not prevent this issue because QHT_DEBUG is currently disabled (the #define is commented out). Found by Linux Verification Center (linuxtesting.org) with SVACE. Reported-by: Alexey Appolonov Signed-off-by: Denis Rastyogin --- util/qht.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/util/qht.c b/util/qht.c index 92c6b78759..cb7e367ebb 100644 --- a/util/qht.c +++ b/util/qht.c @@ -768,6 +768,9 @@ static inline void qht_bucket_remove_entry(struct qht_b= ucket *orig, int pos) return qht_entry_move(orig, pos, b, i - 1); } qht_debug_assert(prev); + if (!prev) { + continue; + } return qht_entry_move(orig, pos, prev, QHT_BUCKET_ENTRIES - 1); } prev =3D b; --=20 2.42.2