From 934e9d137d937706004c325fa1474f9e3f1ba10a Mon Sep 17 00:00:00 2001 From: Christian Bruel Date: Fri, 24 Jan 2025 13:30:43 +0100 Subject: PCI: endpoint: pci-epf-test: Fix double free that causes kernel to oops MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fix a kernel oops found while testing the stm32_pcie Endpoint 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 clear the previous assignment to epf_test->reg[bar]. Then, if the host reboots, the 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. Thus, make sure that pci_epf_alloc_space() and pci_epf_free_space() invocations are symmetric, and as such, set epf_test->reg[bar] to NULL when memory is freed. Reviewed-by: Niklas Cassel Reviewed-by: Manivannan Sadhasivam Signed-off-by: Christian Bruel Link: https://lore.kernel.org/r/20250124123043.96112-1-christian.bruel@foss.st.com [kwilczynski: commit log] Signed-off-by: Krzysztof Wilczyński --- drivers/pci/endpoint/functions/pci-epf-test.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c index 2409787cf56d..bce3ae2c0f65 100644 --- a/drivers/pci/endpoint/functions/pci-epf-test.c +++ b/drivers/pci/endpoint/functions/pci-epf-test.c @@ -738,6 +738,7 @@ static int pci_epf_test_set_bar(struct pci_epf *epf) if (ret) { pci_epf_free_space(epf, epf_test->reg[bar], bar, PRIMARY_INTERFACE); + epf_test->reg[bar] = NULL; dev_err(dev, "Failed to set BAR%d\n", bar); if (bar == test_reg_bar) return ret; @@ -929,6 +930,7 @@ static void pci_epf_test_free_space(struct pci_epf *epf) pci_epf_free_space(epf, epf_test->reg[bar], bar, PRIMARY_INTERFACE); + epf_test->reg[bar] = NULL; } } -- cgit v1.2.3