linux-kernel - Re: [PATCH v2] PCI: endpoint: pci-epf-test: Fix double free Oops

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Message-ID: <20250220152747.GA2510987@rocinante>
Date: Fri, 21 Feb 2025 00:27:47 +0900
From: Krzysztof Wilczyński <kw@...ux.com>
To: Christian Bruel <christian.bruel@...s.st.com>
Cc: manivannan.sadhasivam@...aro.org, kishon@...nel.org,
	bhelgaas@...gle.com, cassel@...nel.org, Frank.Li@....com,
	dlemoal@...nel.org, fabrice.gasnier@...s.st.com,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] PCI: endpoint: pci-epf-test: Fix double free Oops

Hello,

> Fixes an oops found while testing the stm32_pcie ep driver with handling
> of PERST# deassertion:
> 
> During EP initialization, pci_epf_test_alloc_space allocates all BARs,
> which are further freed if epc_set_bar fails (for instance, due to
> no free inbound window).
> 
> However, when pci_epc_set_bar fails, the error path:
>      pci_epc_set_bar -> pci_epf_free_space
> does not reset epf_test->reg[bar].
> 
> Then, if the host reboots, PERST# deassertion restarts the BAR allocation
> sequence with the same allocation failure (no free inbound window),
> creating a double free situation since epf_test->reg[bar] was deallocated
> and is still non-NULL.
> 
> Make sure that pci_epf_alloc_space/pci_epf_free_space are symmetric
> by resetting epf_test->reg[bar] when memory is deallocated.

Applied to endpoint, thank you!

	Krzysztof