From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C6AF58F57 for ; Sun, 16 Jul 2023 20:43:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 49C6FC433C8; Sun, 16 Jul 2023 20:43:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689540237; bh=Ij6xrpprFN7SDHIVIG3FAh9ocTKPdxPTaLqlVAQMQQE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X7nnTBI3jHypXtfIM6MzTdLA1QahMpNY4rnbwTjCIY9F5HORSnbjHe4jMz40gDZya 96CoUY18CkEgMNnNHsn42LuUAecmKwTtcMqbYW/chnqyVgik2SEAjjjCgkItgm91QO m8ENZHkLeJk9Vc09EOBAZ4+QmEvMsJKIvi8u5tUs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Bjorn Helgaas , Ding Hui , Sasha Levin , Zongquan Qin Subject: [PATCH 6.1 292/591] PCI/ASPM: Disable ASPM on MFD function removal to avoid use-after-free Date: Sun, 16 Jul 2023 21:47:11 +0200 Message-ID: <20230716194931.449552451@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194923.861634455@linuxfoundation.org> References: <20230716194923.861634455@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Ding Hui [ Upstream commit 456d8aa37d0f56fc9e985e812496e861dcd6f2f2 ] Struct pcie_link_state->downstream is a pointer to the pci_dev of function 0. Previously we retained that pointer when removing function 0, and subsequent ASPM policy changes dereferenced it, resulting in a use-after-free warning from KASAN, e.g.: # echo 1 > /sys/bus/pci/devices/0000:03:00.0/remove # echo powersave > /sys/module/pcie_aspm/parameters/policy BUG: KASAN: slab-use-after-free in pcie_config_aspm_link+0x42d/0x500 Call Trace: kasan_report+0xae/0xe0 pcie_config_aspm_link+0x42d/0x500 pcie_aspm_set_policy+0x8e/0x1a0 param_attr_store+0x162/0x2c0 module_attr_store+0x3e/0x80 PCIe spec r6.0, sec 7.5.3.7, recommends that software program the same ASPM Control value in all functions of multi-function devices. Disable ASPM and free the pcie_link_state when any child function is removed so we can discard the dangling pcie_link_state->downstream pointer and maintain the same ASPM Control configuration for all functions. [bhelgaas: commit log and comment] Debugged-by: Zongquan Qin Suggested-by: Bjorn Helgaas Fixes: b5a0a9b59c81 ("PCI/ASPM: Read and set up L1 substate capabilities") Link: https://lore.kernel.org/r/20230507034057.20970-1-dinghui@sangfor.com.cn Signed-off-by: Ding Hui Signed-off-by: Bjorn Helgaas Signed-off-by: Sasha Levin --- drivers/pci/pcie/aspm.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 4b4184563a927..74b8183c305df 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1010,21 +1010,24 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev) down_read(&pci_bus_sem); mutex_lock(&aspm_lock); - /* - * All PCIe functions are in one slot, remove one function will remove - * the whole slot, so just wait until we are the last function left. - */ - if (!list_empty(&parent->subordinate->devices)) - goto out; link = parent->link_state; root = link->root; parent_link = link->parent; - /* All functions are removed, so just disable ASPM for the link */ + /* + * link->downstream is a pointer to the pci_dev of function 0. If + * we remove that function, the pci_dev is about to be deallocated, + * so we can't use link->downstream again. Free the link state to + * avoid this. + * + * If we're removing a non-0 function, it's possible we could + * retain the link state, but PCIe r6.0, sec 7.5.3.7, recommends + * programming the same ASPM Control value for all functions of + * multi-function devices, so disable ASPM for all of them. + */ pcie_config_aspm_link(link, 0); list_del(&link->sibling); - /* Clock PM is for endpoint device */ free_link_state(link); /* Recheck latencies and configure upstream links */ @@ -1032,7 +1035,7 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev) pcie_update_aspm_capable(root); pcie_config_aspm_path(parent_link); } -out: + mutex_unlock(&aspm_lock); up_read(&pci_bus_sem); } -- 2.39.2