{"id":2232268,"url":"http://patchwork.ozlabs.org/api/patches/2232268/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260504074823.99377-1-w15303746062@163.com/","project":{"id":28,"url":"http://patchwork.ozlabs.org/api/projects/28/?format=json","name":"Linux PCI development","link_name":"linux-pci","list_id":"linux-pci.vger.kernel.org","list_email":"linux-pci@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260504074823.99377-1-w15303746062@163.com>","list_archive_url":null,"date":"2026-05-04T07:48:23","name":"[v2] char: agp: amd64 - fix broken error propagation in agp_amd64_probe()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"57e28ee041edc3e94e5533c3b5f19aca1d3ffec6","submitter":{"id":93320,"url":"http://patchwork.ozlabs.org/api/people/93320/?format=json","name":null,"email":"w15303746062@163.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260504074823.99377-1-w15303746062@163.com/mbox/","series":[{"id":502621,"url":"http://patchwork.ozlabs.org/api/series/502621/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/list/?series=502621","date":"2026-05-04T07:48:23","name":"[v2] char: agp: amd64 - fix broken error propagation in agp_amd64_probe()","version":2,"mbox":"http://patchwork.ozlabs.org/series/502621/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2232268/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2232268/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=163.com header.i=@163.com header.a=rsa-sha256\n header.s=s110527 header.b=H7olWS5R;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c15:e001:75::12fc:5321; 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The crash occurs in amd64_fetch_size() when attempting\nto dereference the pointer returned by node_to_amd_nb(0).\n\nThe root cause of this crash is broken error propagation in\nagp_amd64_probe(). When no AMD Northbridges are found, cache_nbs()\ncorrectly returns -ENODEV. However, the probe function erroneously\nchecked the return value against exactly -1, rather than < 0.\n\nAs a result, the hardware absence error was masked, allowing the driver\nto improperly proceed with initialization. It eventually called\nagp_add_bridge(), which invokes amd64_fetch_size(). Since the hardware\ndoes not exist, node_to_amd_nb(0) returns NULL, leading to a General\nProtection Fault (GPF) when accessing its ->misc member.\n\nFix the issue by correcting the error check in agp_amd64_probe() to\nabort properly when cache_nbs() returns any negative error code. This\nprevents the driver from erroneously proceeding without hardware, thereby\nresolving the subsequent NULL pointer dereference at its source.\n\nSigned-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn>\n---\n+ Changes in v2:\n+ - Dropped redundant NULL pointer checks in various initialization functions.\n+ - Fixed the actual root cause: broken error propagation in agp_amd64_probe() \n+ where it erroneously checked cache_nbs() against exactly -1 instead of < 0.\n+ (Thanks to Sashiko AI for the review feedback).\n+\n drivers/char/agp/amd64-agp.c | 2 +-\n 1 file changed, 1 insertion(+), 1 deletion(-)","diff":"diff --git a/drivers/char/agp/amd64-agp.c b/drivers/char/agp/amd64-agp.c\nindex 2505df1f4e69..6741270e0a98 100644\n--- a/drivers/char/agp/amd64-agp.c\n+++ b/drivers/char/agp/amd64-agp.c\n@@ -546,7 +546,7 @@ static int agp_amd64_probe(struct pci_dev *pdev,\n \t/* Fill in the mode register */\n \tpci_read_config_dword(pdev, bridge->capndx+PCI_AGP_STATUS, &bridge->mode);\n \n-\tif (cache_nbs(pdev, cap_ptr) == -1) {\n+\tif (cache_nbs(pdev, cap_ptr) < 0) {\n \t\tagp_put_bridge(bridge);\n \t\treturn -ENODEV;\n \t}\n","prefixes":["v2"]}