From nobody Wed Jun 17 01:39:07 2026 Received: from zg8tmtyylji0my4xnjqumte4.icoremail.net (zg8tmtyylji0my4xnjqumte4.icoremail.net [162.243.164.118]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 1C5282773CC for ; Wed, 29 Apr 2026 02:26:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=162.243.164.118 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777429593; cv=none; b=RxIR2zo5AXB27Yvip/66BJporwOpxhYJXusg2/4Z3J6g8eUCxIYIDU9cQlBcGKfaG8Eq9LEKFa0gCd13kyRynDD03K7RQbLRFTolhXy/M7V41/M5NqbmVOXLQnEb3tV1UfKFynFxiEH6KFyIsvuRBOod6abdRA1DEXC2/Q62e1U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777429593; c=relaxed/simple; bh=ag7n+RlkLefXG97nX3VBO1paRb6+K4QuR4rYArk00A4=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=NYi77yMypy7NeP5znhwwj55Bh325atAAeKH4UfIMclhQoU9sOIbtbYw2xPqitog3ojQCFl2VMkgQe/hLEz+uTBvbQaNd6N8Dxo0Kx7ESoP8N0bSwxQQNSNWl5gfVySmJBnZFDMLQiP2nlerGio28N66Xyjz6o+z9k934675iZZ8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=stu.xidian.edu.cn; spf=pass smtp.mailfrom=stu.xidian.edu.cn; dkim=fail (0-bit key) header.d=stu.xidian.edu.cn header.i=@stu.xidian.edu.cn header.b=QZ8o9AQa reason="key not found in DNS"; arc=none smtp.client-ip=162.243.164.118 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=stu.xidian.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=stu.xidian.edu.cn Authentication-Results: smtp.subspace.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=stu.xidian.edu.cn header.i=@stu.xidian.edu.cn header.b="QZ8o9AQa" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=stu.xidian.edu.cn; s=dkim; h=Received:From:To:Cc:Subject:Date: Message-Id:MIME-Version:Content-Transfer-Encoding; bh=xUxjZOTLs3 SQCIpEY0XzIHUHipEp7p2OsBhxI3M3lTE=; b=QZ8o9AQazJjxNLf/aXm0VYAB76 sF/6A6N8Qgrf7/X7YSPoYhBaahiPSSAIiMRm4PdQyyAmkidQUcfZ/8jfdiDx1uHX LNrr8URermKrdHEzzKsFNhf3js0od+ohWTk3VZBXwo5awTLiGLyubs42FuBrIdTd ONU3gxT6i30ATDDpo= Received: from wmy.localdomain (unknown [113.200.174.100]) by hzbj-edu-front-2.icoremail.net (Coremail) with SMTP id BLQMCkC2nLwubPFpjO7SAQ--.8857S2; Wed, 29 Apr 2026 10:26:00 +0800 (CST) From: Mingyu Wang <25181214217@stu.xidian.edu.cn> To: airlied@redhat.com Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Mingyu Wang <25181214217@stu.xidian.edu.cn> Subject: [PATCH] agp: amd64: fix null-ptr-deref in amd64_fetch_size Date: Wed, 29 Apr 2026 10:25:48 +0800 Message-Id: <20260429022548.37070-1-25181214217@stu.xidian.edu.cn> X-Mailer: git-send-email 2.34.1 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 X-CM-TRANSID: BLQMCkC2nLwubPFpjO7SAQ--.8857S2 X-Coremail-Antispam: 1UD129KBjvJXoW7uw1DJFyxuw4rKF18Wr47CFg_yoW8GFyDpr 4rWF1qkw4rGr43Kw4Dtw47A3Z5Zan7WFyYkr9rWwn0vw1kJF1xGry3tFyqqr95A3WvgF45 Aan8tFWUGF10gaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkG14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26r1I6r4UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVCY1x0267AKxVW8JV W8Jr1lnxkEFVAIw20F6cxK64vIFxWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xv F2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r 4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I 648v4I1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67 AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIY rxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14 v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8 JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x0JUq-erUUU UU= X-CM-SenderInfo: qsvrmiqsrujiux6v33wo0lvxldqovvfxof0/1tbiAgUSEWnwzuZQMgAAsX Content-Type: text/plain; charset="utf-8" During the initialization of the amd64_agp driver, the `amd64_fetch_size()` function attempts to retrieve the PCI device pointer from the AMD northbridge descriptor. The code assumes that a valid AMD northbridge always exists when this driver is probed: dev =3D node_to_amd_nb(0)->misc; However, in mixed or emulated environments (e.g., an Intel CPU environment with an AMD AGP bridge passed through or emulated), `node_to_amd_nb(0)` will return NULL. This leads to an immediate null-pointer dereference when attempting to access `->misc`, causing a kernel panic. Fix this by properly checking the return value of `node_to_amd_nb()` before dereferencing it. Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn> --- drivers/char/agp/amd64-agp.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/char/agp/amd64-agp.c b/drivers/char/agp/amd64-agp.c index 2505df1f4e69..1c21787ded69 100644 --- a/drivers/char/agp/amd64-agp.c +++ b/drivers/char/agp/amd64-agp.c @@ -124,9 +124,14 @@ static int amd64_fetch_size(void) int i; u32 temp; struct aper_size_info_32 *values; + struct amd_northbridge *nb; =20 - dev =3D node_to_amd_nb(0)->misc; - if (dev=3D=3DNULL) + nb =3D node_to_amd_nb(0); + if (!nb) + return 0; + + dev =3D nb->misc; + if (!dev) return 0; =20 pci_read_config_dword(dev, AMD64_GARTAPERTURECTL, &temp); --=20 2.34.1