From nobody Sat Jul 25 01:37:31 2026 Received: from mailgw.kylinos.cn (mailgw.kylinos.cn [124.126.103.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75363400E11 for ; Tue, 21 Jul 2026 02:55:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=124.126.103.232 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784602563; cv=none; b=oaGlr0v8iVW0HB5OSqs7PelcC3s78zJnSZgdrmdA5bmJ4P4EcQWx2sxCH2VNxVJCGs+m++NakGkJ8Z5B2pIg5A3qjlpDIPkN0lIoVEP1jVTEOubcSDnKqkY2RCUCCqAZ4UaOT+iE1Fg9HUqiFhfnW9SRZ5ZNJJJ7CS6sKrJEw/w= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784602563; c=relaxed/simple; bh=5Ucjw3gG/NmLiS2yn0lR2lNbe1xThyQBaO7hYoc2ZQQ=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=gvBHaVVd1LnlCKMyn7h3iUwKBjKbZk7AeGf7KGFPpVOJDoTrJUiHFgVVRAMLNnYrS0AT3FxyBBCnX++a506fYNAvd8qe52m7a6x6Ni2WyGuKnmK6h6UTTGlHYvdl6+TplNbjIrehtr1iDWUdBfgtfTvFqTAnWRBujXQ4m0CDDv4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn; spf=pass smtp.mailfrom=kylinos.cn; arc=none smtp.client-ip=124.126.103.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kylinos.cn X-UUID: af1a9f6a84af11f1aa26b74ffac11d73-20260721 X-CTIC-Tags: HR_CC_COUNT, HR_CC_DOMAIN_COUNT, HR_CC_NAME, HR_CC_NO_NAME, HR_CTE_8B HR_CTT_MISS, HR_DATE_H, HR_DATE_WKD, HR_DATE_ZONE, HR_FROM_NAME HR_SJ_DIGIT_LEN, HR_SJ_LANG, HR_SJ_LEN, HR_SJ_LETTER, HR_SJ_NOR_SYM HR_SJ_PHRASE, HR_SJ_PHRASE_LEN, HR_SJ_WS, HR_TO_COUNT, HR_TO_DOMAIN_COUNT HR_TO_NO_NAME, IP_TRUSTED, SRC_TRUSTED, DN_TRUSTED, SA_EXISTED SN_EXISTED, SPF_NOPASS, DKIM_NOPASS, DMARC_NOPASS, CIE_GOOD CIE_GOOD_SPF, GTI_FG_BS, GTI_RG_INFO, GTI_C_BU, AMN_GOOD ABX_MISS_RDNS X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.12,REQID:1fd5b45e-cb73-4503-b2eb-98e222dc0ca7,IP:10, URL:0,TC:0,Content:-5,EDM:25,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTI ON:release,TS:30 X-CID-INFO: VERSION:1.3.12,REQID:1fd5b45e-cb73-4503-b2eb-98e222dc0ca7,IP:10,UR L:0,TC:0,Content:-5,EDM:25,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION :release,TS:30 X-CID-META: VersionHash:e7bac3a,CLOUDID:806a809df66dd85953166b513885721f,BulkI D:2607211055544XJ56OUS,BulkQuantity:0,Recheck:0,SF:17|19|38|66|78|102|127| 850|865|898,TC:nil,Content:0|15|50,EDM:5,IP:-2,URL:0,File:nil,RT:nil,Bulk: nil,QS:nil,BEC:nil,COL:0,OSI:0,OSA:0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,B RE:0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR,TF_CID_SPAM_FAS,TF_CID_SPAM_FSD X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: af1a9f6a84af11f1aa26b74ffac11d73-20260721 X-User: wangxuewen@kylinos.cn Received: from localhost.localdomain [(223.70.159.239)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 1994862755; Tue, 21 Jul 2026 10:55:51 +0800 From: Xuewen Wang To: chenhuacai@kernel.org, kernel@xen0n.name Cc: loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, Xuewen Wang Subject: [PATCH v1] LoongArch: pci: add NULL check for map_bus return value in loongson_gpu_fixup_dma_hang Date: Tue, 21 Jul 2026 10:55:36 +0800 Message-Id: <20260721025536.1484464-1-wangxuewen@kylinos.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The map_bus() callback can return NULL when the target device does not exist (e.g. non-existent device hidden by FLAG_DEV_HIDDEN, or device > 0 on internal bridges). All other callers in the kernel check the return value, but loongson_gpu_fixup_dma_hang() uses it directly, leading to a null pointer dereference via readw(base + PCI_DEVICE_ID). Add the missing NULL check to prevent the crash. Fixes: 95db0c9f526d ("LoongArch: Workaround LS2K/LS7A GPU DMA hang bug") Signed-off-by: Xuewen Wang --- arch/loongarch/pci/pci.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/loongarch/pci/pci.c b/arch/loongarch/pci/pci.c index f33c7ea1443d..3cd89b0224e3 100644 --- a/arch/loongarch/pci/pci.c +++ b/arch/loongarch/pci/pci.c @@ -115,6 +115,11 @@ static void loongson_gpu_fixup_dma_hang(struct pci_dev= *pdev, bool on) static u32 crtc_status[CRTC_NUM_MAX] =3D { 0 }; =20 base =3D pdev->bus->ops->map_bus(pdev->bus, pdev->devfn + 1, 0); + if (!base) { + pci_dbg(pdev, "cannot map config space for devfn %02x.%d\n", + PCI_SLOT(pdev->devfn + 1), PCI_FUNC(pdev->devfn + 1)); + return; + } device =3D readw(base + PCI_DEVICE_ID); =20 regbase =3D ioremap(readq(base + PCI_BASE_ADDRESS_0) & ~0xffull, SZ_64K); --=20 2.25.1