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 9F736194083; Tue, 13 Aug 2024 10:37:33 +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=1723545453; cv=none; b=XJ9q9dZmLP/H3tdKY4T0j1vkylH+x+1RodaMfPbX5Y4z3WfCzztMz/bvTwEM5gCi1zjA4DGDPn4IFhYNypnoY48HfeBhM/3YII8kQBR1mMEGfNzsEIJohdQiKELIq1YYoEv25YyaUh2flr/OJK0BxQYYLOI4Bma/7a+s1L1Evx8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723545453; c=relaxed/simple; bh=lW1qjs04AbAiMwjIgti1TMx0YBebE/C8dqm9HUmHRT0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fpQRkVCDUAhhFYQzkPO1tE31VZGEK3Kum/yIQf4Vaje2xvhv2EJ3k+MFoXZjaR/0S5Q0oILjF9K3HZx2blcAJvaCjT4MGNgSA26YH1t9S/+oGn85HV31IHMjAAAhBBGkmiqvrUuN0orUw7ThE/fxzSKrPb+AAzmrKYE63oH4z0A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tMG2dG6W; 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="tMG2dG6W" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C57BC4AF11; Tue, 13 Aug 2024 10:37:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723545453; bh=lW1qjs04AbAiMwjIgti1TMx0YBebE/C8dqm9HUmHRT0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tMG2dG6WcpEYvQzQVjVOTn6bKA8nbvWK3KodDuIY/6rJ21w9cjiEzQjG0o5RYizex zeiNI4Ihgv2j7qo0zq/oFYlgfn30io3SBpq+p2UZzMATWLwU9oT3pW8zTGohq5L5Ul JmdWgI0GdBXOAAgHtOntLu4ZJcNUloKMEzSilCmM= Date: Tue, 13 Aug 2024 12:37:30 +0200 From: Greg Kroah-Hartman To: Lukas Wunner Cc: Sasha Levin , stable@vger.kernel.org, linux-pci@vger.kernel.org, Keith Busch , Mika Westerberg , Bjorn Helgaas , Krzysztof Wilczynski Subject: Re: [PATCH 5.10-stable] PCI/DPC: Fix use-after-free on concurrent DPC and hot-removal Message-ID: <2024081319-scruffy-faster-3311@gregkh> References: <4d4ac43578f9aad9d7eee85a51833ae5e4b7cdb3.1722335040.git.lukas@wunner.de> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4d4ac43578f9aad9d7eee85a51833ae5e4b7cdb3.1722335040.git.lukas@wunner.de> On Tue, Jul 30, 2024 at 12:26:55PM +0200, Lukas Wunner wrote: > 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+ > --- > drivers/pci/pci.c | 19 ++++++++++++------- > 1 file changed, 12 insertions(+), 7 deletions(-) > Both now queued up, thanks. greg k-h