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 7AED6F99C7C for ; Sat, 18 Apr 2026 12:12:31 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B385410E0B9; Sat, 18 Apr 2026 12:12:30 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="m1yjrDgC"; dkim-atps=neutral Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4160C10E0B9; Sat, 18 Apr 2026 12:12:30 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id D1C3A43832; Sat, 18 Apr 2026 12:12:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 86DDCC19424; Sat, 18 Apr 2026 12:12:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776514349; bh=b9PenJjHaSudWajbzycGmt+Iph3cnRU02bJt70Fh7Eg=; h=Date:Subject:Cc:To:From:References:In-Reply-To:From; b=m1yjrDgC2Vp3S9i2v6ibSL2JFghRG5C7W0hZT+LalgTRV1d7OnryWOSB6nnndhnYp dCbOL2num5eSmqu1bDi587r/2SOMZZa1nqWxhLf7M7JjN94lkCjoVu93rtzCfiuyzO NrF+DTMCzFGk+MYZGmNkqPxPJR+4SfVS4d7MdRsFaZuPBJoj53dseGveTtyZHtHA5e NKuYe8ftmP7kAh+2zEn9XPYZOL/ffb/0+53Ko/kcS2f4XDAplXWcFI2Ca0k5t57/xE CckFwhX1B9mrP2MOo7YpWRCfuj+3OuukgNtaYIFU785F7YAIjUnmC3XCOP4qKcb0pF Xg5ix46JWpC5A== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sat, 18 Apr 2026 14:12:25 +0200 Message-Id: Subject: Re: [PATCH] drm/nouveau/gsp: Fix possible NULL pointer dereference warning in r535_dmac_alloc Cc: , , , , , , , , , "sunliming" To: From: "Danilo Krummrich" References: <20260418071412.86022-1-sunliming@linux.dev> In-Reply-To: <20260418071412.86022-1-sunliming@linux.dev> 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Sat Apr 18, 2026 at 9:14 AM CEST, sunliming wrote: > From: sunliming > > Fix below smatch warnings: > drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c:178 r535_dmac_allo= c() > warn: 'args' can also be NULL Please write a commit description that explains also the underlying problem= ; see more below. > Signed-off-by: sunliming > --- > drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c b/dri= vers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c > index 6e63df816d85..6dec2623d0be 100644 > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c > @@ -172,6 +172,8 @@ r535_dmac_alloc(struct nvkm_disp *disp, u32 oclass, i= nt inst, u32 put_offset, > =20 > args =3D nvkm_gsp_rm_alloc_get(&disp->rm.object, (oclass << 16) | inst,= oclass, > sizeof(*args), dmac); > + if (!args) > + return -ENOMEM; Are we sure that this can ever return NULL in the first place? I know that nvkm_gsp_rm_alloc_get() internally checks for IS_ERR_OR_NULL(), but I could= n't find anything within the callchain that would actually return NULL. That said, I think IS_ERR_OR_NULL() checks are misleading. > if (IS_ERR(args)) > return PTR_ERR(args); > =20 > --=20 > 2.25.1 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 898E5F99C7F for ; Sat, 18 Apr 2026 12:12:34 +0000 (UTC) Received: from kara.freedesktop.org (unknown [131.252.210.166]) by gabe.freedesktop.org (Postfix) with ESMTPS id BC02810E339; Sat, 18 Apr 2026 12:12:32 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="m1yjrDgC"; dkim-atps=neutral Received: from kara.freedesktop.org (localhost [127.0.0.1]) by kara.freedesktop.org (Postfix) with ESMTP id D65BD45A47; 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Sat, 18 Apr 2026 12:12:30 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id D1C3A43832; Sat, 18 Apr 2026 12:12:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 86DDCC19424; Sat, 18 Apr 2026 12:12:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776514349; bh=b9PenJjHaSudWajbzycGmt+Iph3cnRU02bJt70Fh7Eg=; h=Date:Subject:Cc:To:From:References:In-Reply-To:From; b=m1yjrDgC2Vp3S9i2v6ibSL2JFghRG5C7W0hZT+LalgTRV1d7OnryWOSB6nnndhnYp dCbOL2num5eSmqu1bDi587r/2SOMZZa1nqWxhLf7M7JjN94lkCjoVu93rtzCfiuyzO NrF+DTMCzFGk+MYZGmNkqPxPJR+4SfVS4d7MdRsFaZuPBJoj53dseGveTtyZHtHA5e NKuYe8ftmP7kAh+2zEn9XPYZOL/ffb/0+53Ko/kcS2f4XDAplXWcFI2Ca0k5t57/xE CckFwhX1B9mrP2MOo7YpWRCfuj+3OuukgNtaYIFU785F7YAIjUnmC3XCOP4qKcb0pF Xg5ix46JWpC5A== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sat, 18 Apr 2026 14:12:25 +0200 Message-Id: Subject: Re: [PATCH] drm/nouveau/gsp: Fix possible NULL pointer dereference warning in r535_dmac_alloc To: From: "Danilo Krummrich" References: <20260418071412.86022-1-sunliming@linux.dev> In-Reply-To: <20260418071412.86022-1-sunliming@linux.dev> Message-ID-Hash: D4GZTQ7D6VQJEQOVJX5Y4W34LCXNMTUE X-Message-ID-Hash: D4GZTQ7D6VQJEQOVJX5Y4W34LCXNMTUE X-MailFrom: dakr@kernel.org X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: maarten.lankhorst@linux.intel.com, mripard@kernel.org, simona@ffwll.ch, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, sunliming X-Mailman-Version: 3.3.8 Precedence: list List-Id: Nouveau development list Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Sat Apr 18, 2026 at 9:14 AM CEST, sunliming wrote: > From: sunliming > > Fix below smatch warnings: > drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c:178 r535_dmac_allo= c() > warn: 'args' can also be NULL Please write a commit description that explains also the underlying problem= ; see more below. > Signed-off-by: sunliming > --- > drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c b/dri= vers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c > index 6e63df816d85..6dec2623d0be 100644 > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/disp.c > @@ -172,6 +172,8 @@ r535_dmac_alloc(struct nvkm_disp *disp, u32 oclass, i= nt inst, u32 put_offset, > =20 > args =3D nvkm_gsp_rm_alloc_get(&disp->rm.object, (oclass << 16) | inst,= oclass, > sizeof(*args), dmac); > + if (!args) > + return -ENOMEM; Are we sure that this can ever return NULL in the first place? I know that nvkm_gsp_rm_alloc_get() internally checks for IS_ERR_OR_NULL(), but I could= n't find anything within the callchain that would actually return NULL. That said, I think IS_ERR_OR_NULL() checks are misleading. > if (IS_ERR(args)) > return PTR_ERR(args); > =20 > --=20 > 2.25.1