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 0AA521A76A1; Tue, 30 Jul 2024 17:23:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722360231; cv=none; b=Ka6NTBken4LH45qk1Jq/Q3k35kXTdMb1N6z5j1hi7uk3IP47mVScFgf86/HTSoTWrzPYoeb78RL4I6DzOCJUP4r6qxTzqrhu0FNuTssy43nNb+zFA4b3TvV+1NQ4lXDPF0Lsr2hv6GldAxNc1wNUaqz1MbCemFiqLXp0l5dMn0A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722360231; c=relaxed/simple; bh=3GuqdPMTXjSeF05eEsxUzJ2YH4IhSUbIt8HdNoO4nc8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=S6WJgGS5S7M6Ixh+Swl12kmUsfl8ViE7Y+qMSE2tX/rCynJM1lWGOac1uSM/dSfQ8FnaHOB4G2NFZ+8yE8IH+ImTlEdKQZgB/Qu+JIR/g2uXSscSPl11/PJ8KlFFutWP6NwoLEUdnQnzZVCrpbfx8WKhbSF/YE9v6cN9nrRhY+Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=q9+cse+u; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="q9+cse+u" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6EC27C32782; Tue, 30 Jul 2024 17:23:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1722360230; bh=3GuqdPMTXjSeF05eEsxUzJ2YH4IhSUbIt8HdNoO4nc8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q9+cse+ub+p07Wci+VMbb3QKDlzK+Bat/+MRP5M9NKizSYL+xpjrK+TT6JpXmZHST sbZ2hWiWC/5l2eTAo+YCfjJwq+mJ2HgeEDNmpS/AOBl7nPTc6I2NFmuWxH5qXKLBub 0J/o9yFkD95qaII2aNerpOK8TqZazBaDXYK3u6F0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Keith Busch , Lukas Wunner , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , Mika Westerberg Subject: [PATCH 6.10 637/809] PCI/DPC: Fix use-after-free on concurrent DPC and hot-removal Date: Tue, 30 Jul 2024 17:48:33 +0200 Message-ID: <20240730151750.006343258@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240730151724.637682316@linuxfoundation.org> References: <20240730151724.637682316@linuxfoundation.org> User-Agent: quilt/0.67 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Wunner commit 11a1f4bc47362700fcbde717292158873fb847ed upstream. Keith reports a use-after-free when a DPC event occurs concurrently to hot-removal of the same portion of the hierarchy: The dpc_handler() awaits readiness of the secondary bus below the Downstream Port where the DPC event occurred. To do so, it polls the config space of the first child device on the secondary bus. If that child device is concurrently removed, accesses to its struct pci_dev cause the kernel to oops. That's because pci_bridge_wait_for_secondary_bus() neglects to hold a reference on the child device. Before v6.3, the function was only called on resume from system sleep or on runtime resume. Holding a reference wasn't necessary back then because the pciehp IRQ thread could never run concurrently. (On resume from system sleep, IRQs are not enabled until after the resume_noirq phase. And runtime resume is always awaited before a PCI device is removed.) However starting with v6.3, pci_bridge_wait_for_secondary_bus() is also called on a DPC event. Commit 53b54ad074de ("PCI/DPC: Await readiness of secondary bus after reset"), which introduced that, failed to appreciate that pci_bridge_wait_for_secondary_bus() now needs to hold a reference on the child device because dpc_handler() and pciehp may indeed run concurrently. The commit was backported to v5.10+ stable kernels, so that's the oldest one affected. Add the missing reference acquisition. Abridged stack trace: BUG: unable to handle page fault for address: 00000000091400c0 CPU: 15 PID: 2464 Comm: irq/53-pcie-dpc 6.9.0 RIP: pci_bus_read_config_dword+0x17/0x50 pci_dev_wait() pci_bridge_wait_for_secondary_bus() dpc_reset_link() pcie_do_recovery() dpc_handler() Fixes: 53b54ad074de ("PCI/DPC: Await readiness of secondary bus after reset") Closes: https://lore.kernel.org/r/20240612181625.3604512-3-kbusch@meta.com/ Link: https://lore.kernel.org/linux-pci/8e4bcd4116fd94f592f2bf2749f168099c480ddf.1718707743.git.lukas@wunner.de Reported-by: Keith Busch Tested-by: Keith Busch Signed-off-by: Lukas Wunner Signed-off-by: Krzysztof Wilczyński Reviewed-by: Keith Busch Reviewed-by: Mika Westerberg Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Greg Kroah-Hartman --- drivers/pci/pci.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4753,7 +4753,7 @@ static int pci_bus_max_d3cold_delay(cons */ int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type) { - struct pci_dev *child; + struct pci_dev *child __free(pci_dev_put) = NULL; int delay; if (pci_dev_is_disconnected(dev)) @@ -4782,8 +4782,8 @@ int pci_bridge_wait_for_secondary_bus(st return 0; } - child = list_first_entry(&dev->subordinate->devices, struct pci_dev, - bus_list); + child = pci_dev_get(list_first_entry(&dev->subordinate->devices, + struct pci_dev, bus_list)); up_read(&pci_bus_sem); /*