From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C3B9145FFCB; Tue, 25 Aug 2026 13:33:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787664812; cv=none; b=ASjKER7ayLaKo1idhbVNUzwUv4APKCFpxOnQwuSpLm44/6moVWK7p5s0vifhjO5I4YMqmfNboUbIaY0NyNxQ6UHeTqZq4t/wdNiDIaMEFYkkRqmc8Hp2klpD0hRsfOoV5eFkMV7gcu9gDluAhwckgKnnoErKBk7Jq8ZvbnP19yc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787664812; c=relaxed/simple; bh=WnAq3iVc/kbL3NhDxZ2Rt1a8Tqzw3YchRFzTNVuNsww=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EhmkhVW9YzgGVNOF8Eud1bhhcvT8T43gHb5kPmbqHv/t4sbfHy4S/gmUr9RHI9FO/Rl8VsupcmMoK8CWFLq+I0McoqMmwYzWtmrMlG0CTmRRjyXB3pMXcIcweBf8S9vJ6jVUmSNiOTMTFKpCuwskTbDbNtRtSXphrZzCkF51fX8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=INNLS4gW; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="INNLS4gW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DADF31F00A3A; Tue, 25 Aug 2026 13:33:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787664810; bh=N3Wt8he+24HkEOrIuVIyxgKGrZuCtOLHoH4I9anpBeQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=INNLS4gWXUz4KykS9btdgGqpNWIkf3vPL6dR9gQQ1qE/EpQ/0Dz1+gUnB7ellaBp+ 1XtUSyqXuMCyY/M0J0vKLoW8KDZrESOge/1mwIUfRzvJs00Xk6Ka7wslIiJiqT6RXW lVcKiUyR83bE2xmbETAsRwK9z12emSmdhjbUNlqI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Steffen Persvold , Manivannan Sadhasivam Subject: [PATCH 7.1 005/101] PCI: host-generic: Fix NULL pointer dereference on 32-bit CAM systems Date: Tue, 25 Aug 2026 15:24:43 +0200 Message-ID: <20260825132542.212354798@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.986300899@linuxfoundation.org> References: <20260825132541.986300899@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steffen Persvold commit 008cb88edb41f3c7c8e0ed763ff9f26719830984 upstream. On 32-bit systems the config space is too large to ioremap in one go, so pci_ecam_create() maps each bus segment separately and relies on the ->add_bus callback (pci_ecam_add_bus) to populate the per-bus mapping in cfg->winp[]. pci_ecam_map_bus() then uses that mapping as the base for every config access. The generic ECAM ops (pci_generic_ecam_ops) already provide the ->add_bus and ->remove_bus callbacks, but the CAM (legacy) ops in pci-host-generic.c do not. As a result, on a 32-bit host using "pci-host-cam-generic" the per-bus mapping is never set up and the first config read dereferences a NULL base, crashing during bus enumeration: Unable to handle kernel NULL pointer dereference at virtual address 00000800 Oops [#1] CPU: 0 PID: 1 Comm: swapper Not tainted 6.9.7+ #43 Hardware name: Digilent Nexys-Video-A7 RV32 (DT) epc : pci_generic_config_read+0x40/0xb0 ra : pci_generic_config_read+0x2c/0xb0 [] pci_generic_config_read+0x40/0xb0 [] pci_bus_read_config_dword+0x50/0xb0 [] pci_bus_generic_read_dev_vendor_id+0x3c/0x1ec [] pci_scan_single_device+0xa4/0x11c [] pci_scan_slot+0x9c/0x23c [] pci_scan_child_bus_extend+0x58/0x2f4 [] pci_scan_root_bus_bridge+0x64/0xe8 [] pci_host_probe+0x20/0xc8 [] pci_host_common_probe+0x144/0x1e4 Fix this by giving the CAM ops the same ->add_bus/->remove_bus callbacks. Since pci_ecam_add_bus() and pci_ecam_remove_bus() are static to ecam.c, move the CAM ops definition there as pci_generic_cam_ops (mirroring pci_generic_ecam_ops) and export it for pci-host-generic.c to reference. Fixes: 8fe55ef23387 ("PCI: Dynamically map ECAM regions") Signed-off-by: Steffen Persvold [mani: removed timestamp from log] Signed-off-by: Manivannan Sadhasivam Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260709122446.3151899-1-spersvold@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/pci/controller/pci-host-generic.c | 11 +---------- drivers/pci/ecam.c | 13 +++++++++++++ include/linux/pci-ecam.h | 3 +++ 3 files changed, 17 insertions(+), 10 deletions(-) --- a/drivers/pci/controller/pci-host-generic.c +++ b/drivers/pci/controller/pci-host-generic.c @@ -16,15 +16,6 @@ #include "pci-host-common.h" -static const struct pci_ecam_ops gen_pci_cfg_cam_bus_ops = { - .bus_shift = 16, - .pci_ops = { - .map_bus = pci_ecam_map_bus, - .read = pci_generic_config_read, - .write = pci_generic_config_write, - } -}; - static bool pci_dw_valid_device(struct pci_bus *bus, unsigned int devfn) { struct pci_config_window *cfg = bus->sysdata; @@ -60,7 +51,7 @@ static const struct pci_ecam_ops pci_dw_ static const struct of_device_id gen_pci_of_match[] = { { .compatible = "pci-host-cam-generic", - .data = &gen_pci_cfg_cam_bus_ops }, + .data = &pci_generic_cam_ops }, { .compatible = "pci-host-ecam-generic", .data = &pci_generic_ecam_ops }, --- a/drivers/pci/ecam.c +++ b/drivers/pci/ecam.c @@ -208,6 +208,19 @@ const struct pci_ecam_ops pci_generic_ec }; EXPORT_SYMBOL_GPL(pci_generic_ecam_ops); +/* CAM ops */ +const struct pci_ecam_ops pci_generic_cam_ops = { + .bus_shift = 16, + .pci_ops = { + .add_bus = pci_ecam_add_bus, + .remove_bus = pci_ecam_remove_bus, + .map_bus = pci_ecam_map_bus, + .read = pci_generic_config_read, + .write = pci_generic_config_write, + } +}; +EXPORT_SYMBOL_GPL(pci_generic_cam_ops); + #if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS) /* ECAM ops for 32-bit access only (non-compliant) */ const struct pci_ecam_ops pci_32b_ops = { --- a/include/linux/pci-ecam.h +++ b/include/linux/pci-ecam.h @@ -81,6 +81,9 @@ void __iomem *pci_ecam_map_bus(struct pc /* default ECAM ops */ extern const struct pci_ecam_ops pci_generic_ecam_ops; +/* default CAM ops */ +extern const struct pci_ecam_ops pci_generic_cam_ops; + #if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS) extern const struct pci_ecam_ops pci_32b_ops; /* 32-bit accesses only */ extern const struct pci_ecam_ops pci_32b_read_ops; /* 32-bit read only */