From nobody Wed Apr 15 02:40:31 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C03CAC04A68 for ; Wed, 27 Jul 2022 09:08:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231640AbiG0JIm (ORCPT ); Wed, 27 Jul 2022 05:08:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231624AbiG0JHQ (ORCPT ); Wed, 27 Jul 2022 05:07:16 -0400 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5DDB43E46 for ; Wed, 27 Jul 2022 02:07:07 -0700 (PDT) Received: by mail-pf1-x441.google.com with SMTP id d10so15559936pfd.9 for ; Wed, 27 Jul 2022 02:07:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id; bh=2Sl2t8r1ZUfe8lzmXAHqvujfGWqYPzoD6dESsmixId8=; b=jjJ8BeO4eC8mXVDiID2bspJ1p6dBYwNpZawCx7rWSN/pqy2FJOuzecozYhRBwoldNn f/t3D/gjmmb6JJJVhf7hcdfnOiDsB8dgoCMy0I6+H4NVV09QkCfNmXE0SyB442KdPbXl U5tJwou8ONIH1L7pnBUVHQoRnG+lMCkD47QcG3oPqTY61VSiaHuMJer+EKmOCof9BoJH O+wkFKCEWTKHyIxLtAjISdk0ZIBIcEemJ/buJxMinEfqW+P9dcx2wKe0mpz+t5SABFiQ KfxUzMpbF2z6NcV3Ern1UjZyV9OFIx+BgAHkXcg4hjgvTQUB427AFWAXFbmMzLCuUMRX uDJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=2Sl2t8r1ZUfe8lzmXAHqvujfGWqYPzoD6dESsmixId8=; b=e1abb1+7FF9enUSR7L2ST1g2V5xZgnmU2lBBKKPZRXw0a3PSw0PYie4Mgua64Vckwl IIrqcA4Omjz8spEe/YMcKdZDuRy0BTqZSVE7k3CB2MQltNDU5c6Jc1x+PBwjb6jvlvgV DadJwXTR3Hiun09Ot003r1mOqUqg4WIIKFcI7X5SIH1TTMkHmLIzlCD6PlB0Fh1sgs+v LgDIBtyWzHcu3lzxpAksYPDQZsp02RUu4OSjamz+PN7ssI98YpvLYiRBEgq2/MDj5+tD 99HaEusqVdC8u4OdaSju2c271588P7J7o2jUdqaKPGdy3oESmsvRIKByF0L2FWespQjP kAAw== X-Gm-Message-State: AJIora87CbggCU/pgGMWRWh2s4+2sz8RBMQ5SRBU0fKLtoGTY6OytP2W c5dYZWdXaYWsnkKXLYxbqov6Dg== X-Google-Smtp-Source: AGRyM1vtuT/ZYh9CUtmNfGXr7qX1Z6Jxa2DeJOGGWDtXWejTkzZSlxUordVbZUp7hABJPSZZiRQ9AA== X-Received: by 2002:a63:4c0d:0:b0:41a:77fe:2bc8 with SMTP id z13-20020a634c0d000000b0041a77fe2bc8mr17722286pga.82.1658912827076; Wed, 27 Jul 2022 02:07:07 -0700 (PDT) Received: from n131-251-112.byted.org ([121.30.179.125]) by smtp.gmail.com with ESMTPSA id x8-20020a170902a38800b0016c46ff1973sm13131587pla.228.2022.07.27.02.07.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Jul 2022 02:07:06 -0700 (PDT) From: tujinjiang@bytedance.com To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jinjiang Tu Subject: [PATCH] vmscan: fix potential arbitrary pointer passed to kfree in unregister_shrinker Date: Wed, 27 Jul 2022 17:07:00 +0800 Message-Id: <20220727090700.3238-1-tujinjiang@bytedance.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Jinjiang Tu when shrinker is registered with SHRINKER_MEMCG_AWARE flag, register_shrinker will not initialize shrinker->nr_deferred, but the pointer will be passed to kfree in unregister_shrinker when the shrinker is unregistered. This leads to kernel crash when the shrinker object is dynamically allocated. To fix it, this patch initialize shrinker->nr_deferred at the beginning of prealloc_shrinker. Signed-off-by: Jinjiang Tu --- mm/vmscan.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index f7d9a683e3a7..06ab5a398971 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -613,6 +613,7 @@ int prealloc_shrinker(struct shrinker *shrinker) unsigned int size; int err; =20 + shrinker->nr_deferred =3D NULL; if (shrinker->flags & SHRINKER_MEMCG_AWARE) { err =3D prealloc_memcg_shrinker(shrinker); if (err !=3D -ENOSYS) --=20 2.17.1