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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0C661C44515 for ; Fri, 17 Jul 2026 21:06:05 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 28B8510F624; Fri, 17 Jul 2026 21:06:03 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="fI5wceFA"; dkim-atps=neutral Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by gabe.freedesktop.org (Postfix) with ESMTPS id C4CED10F626 for ; Fri, 17 Jul 2026 21:06:01 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 48C1F60051; Fri, 17 Jul 2026 21:06:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C84F61F000E9; Fri, 17 Jul 2026 21:06:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784322361; bh=2EvCGMwl8Wy6kd16GoNLUKOx67Gcj22P6xondvQAUPo=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=fI5wceFAA1V2GJ5i0mhOyzeZDNM6yFXY3dyLxkjAqjsQmGBgjAqov+CrQfc4wcweg sdxN3aylZyVV0NkqsPU98JQp5SlBvxFVLs6OJ4y1M0dTFxpeOSZYQqfYViw37YGaKQ /mKQQp4emrMLUVVW9YUptiwjGYXQVYxPieWLd5gOu4OWXyUrs8f2FiX6j/xjr4r0ff FDcS9TkhjwwqcePf86Et8b5YdqED1rmk4qgvlRu2EpWUgOjKFKG64U6FOCsERP+/fQ oGbdqgFUGPP5KZOfOtYfo886jn4SvyVGZrZt16b2uH8NFHMNboU39ieH4DyQ/3HgfJ RwJzshg6Ksm9w== From: sashiko-bot@kernel.org Subject: Re: [PATCH v6 11/16] drm/msm/gem: Set resv before exposing obj To: "Rob Clark" Cc: dri-devel@lists.freedesktop.org In-Reply-To: <20260717204841.26120-12-robin.clark@oss.qualcomm.com> References: <20260717204841.26120-1-robin.clark@oss.qualcomm.com> <20260717204841.26120-12-robin.clark@oss.qualcomm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 17 Jul 2026 21:06:00 +0000 Message-Id: <20260717210600.C84F61F000E9@smtp.kernel.org> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Thank you for your contribution! Sashiko AI review found 2 potential issue(= s) to consider: New issues: - [Low] The patch modifies the signature of msm_gem_new() from 3 to 4 argum= ents but fails to update the caller in drivers/gpu/drm/msm/disp/mdp4/mdp4_k= ms.c. This results in a compiler error ('too few arguments to function'). Pre-existing issues: - [Critical] Missing NULL check for the return value of msm_context_vm() le= ads to a kernel panic when dereferenced by drm_gpuvm_resv_obj(). This probl= em wasn't introduced by this patch, but remains a critical vulnerability. -- --- Patch [11]: [PATCH v6 11/16] drm/msm/gem: Set resv before exposing obj = --- commit 96533966332980b8f99abb5ba08db109f97b565b Author: Rob Clark drm/msm/gem: Set resv before exposing obj Don't swap the resv object _after_ exposing the newly created obj in LRU or global objects list, as that creates a race condition where another thread could lock the object using the original (per-obj) resv, but then unlock after the resv is replaced. > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c > index 961e22d3c7292..12d9b8a9c360a 100644 > --- a/drivers/gpu/drm/msm/msm_gem.c > +++ b/drivers/gpu/drm/msm/msm_gem.c [ ... ] > @@ -1135,10 +1135,17 @@ int msm_gem_new_handle(struct drm_device *dev, st= ruct drm_file *file, > size_t size, uint32_t flags, uint32_t *handle, > char *name) > { > - struct drm_gem_object *obj; > + struct drm_gem_object *obj, *r_obj =3D NULL; > int ret; > =20 > - obj =3D msm_gem_new(dev, size, flags); > + if (flags & MSM_BO_NO_SHARE) { > + struct msm_context *ctx =3D file->driver_priv; > + struct drm_gpuvm *vm =3D msm_context_vm(dev, ctx); > + > + r_obj =3D drm_gpuvm_resv_obj(vm); [Severity: Critical] This is a pre-existing issue, but can msm_context_vm() return NULL here? If this runs on a KMS-only configuration where no GPU is bound,=20 msm_context_vm() can return NULL. When passed to drm_gpuvm_resv_obj(vm), would this cause a NULL pointer dereference since the macro expands to ((vm)->r_obj)? Since unprivileged userspace can trigger this path via the MSM_GEM_NEW ioctl with the MSM_BO_NO_SHARE flag, should a NULL check be added before accessing vm? > + } > + > + obj =3D msm_gem_new(dev, size, flags, r_obj); [ ... ] > diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h > index 762e546d25ef3..47ff2bbc19150 100644 > --- a/drivers/gpu/drm/msm/msm_gem.h > +++ b/drivers/gpu/drm/msm/msm_gem.h > @@ -296,7 +296,7 @@ int msm_gem_cpu_fini(struct drm_gem_object *obj); > int msm_gem_new_handle(struct drm_device *dev, struct drm_file *file, > size_t size, uint32_t flags, uint32_t *handle, char *name); > struct drm_gem_object *msm_gem_new(struct drm_device *dev, > - size_t size, uint32_t flags); > + size_t size, uint32_t flags, struct drm_gem_object *r_obj); [Severity: Low] Does this change miss updating some callers? Looking at mdp4_kms_init() in drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c, it still calls msm_gem_new() with only 3 arguments: mdp4_kms->blank_cursor_bo =3D msm_gem_new(dev, SZ_16K, MSM_BO_WC | MSM_BO_S= CANOUT); Could this cause a build failure when CONFIG_DRM_MSM_MDP4 is enabled due to too few arguments? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260717204841.2612= 0-1-robin.clark@oss.qualcomm.com?part=3D11