[PATCH] PCI: Fix use-after-free in pci_bus_release_domain_nr()
From: Rob Herring
Date: Wed Mar 29 2023 - 08:39:07 EST
Commit c14f7ccc9f5d ("PCI: Assign PCI domain IDs by ida_alloc()")
introduced a use-after-free bug in the bus removal cleanup. The issue
was found with kfence:
[ 19.285870] ==================================================================
[ 19.293351] BUG: KFENCE: use-after-free read in pci_bus_release_domain_nr+0x10/0x70
[ 19.302817] Use-after-free read at 0x000000007f3b80eb (in kfence-#115):
[ 19.309677] pci_bus_release_domain_nr+0x10/0x70
[ 19.309691] dw_pcie_host_deinit+0x28/0x78
[ 19.309702] tegra_pcie_deinit_controller+0x1c/0x38 [pcie_tegra194]
[ 19.309734] tegra_pcie_dw_probe+0x648/0xb28 [pcie_tegra194]
[ 19.309752] platform_probe+0x90/0xd8
[ 19.309764] really_probe+0xb8/0x298
[ 19.309777] __driver_probe_device+0x78/0xd8
[ 19.309788] driver_probe_device+0x38/0x120
[ 19.309799] __device_attach_driver+0x94/0xe0
[ 19.309812] bus_for_each_drv+0x70/0xc8
[ 19.309822] __device_attach+0xfc/0x188
[ 19.309833] device_initial_probe+0x10/0x18
[ 19.309844] bus_probe_device+0x94/0xa0
[ 19.309854] deferred_probe_work_func+0x80/0xb8
[ 19.309864] process_one_work+0x1e0/0x348
[ 19.309882] worker_thread+0x48/0x410
[ 19.309891] kthread+0xf4/0x110
[ 19.309904] ret_from_fork+0x10/0x20
[ 19.311457] kfence-#115: 0x00000000063a155a-0x00000000ba698da8, size=1072, cache=kmalloc-2k
[ 19.311469] allocated by task 96 on cpu 10 at 19.279323s:
[ 19.311562] __kmem_cache_alloc_node+0x260/0x278
[ 19.311571] kmalloc_trace+0x24/0x30
[ 19.311580] pci_alloc_bus+0x24/0xa0
[ 19.311590] pci_register_host_bridge+0x48/0x4b8
[ 19.311601] pci_scan_root_bus_bridge+0xc0/0xe8
[ 19.311613] pci_host_probe+0x18/0xc0
[ 19.311623] dw_pcie_host_init+0x2c0/0x568
[ 19.311630] tegra_pcie_dw_probe+0x610/0xb28 [pcie_tegra194]
[ 19.311647] platform_probe+0x90/0xd8
[ 19.311653] really_probe+0xb8/0x298
[ 19.311663] __driver_probe_device+0x78/0xd8
[ 19.311672] driver_probe_device+0x38/0x120
[ 19.311682] __device_attach_driver+0x94/0xe0
[ 19.311694] bus_for_each_drv+0x70/0xc8
[ 19.311702] __device_attach+0xfc/0x188
[ 19.311713] device_initial_probe+0x10/0x18
[ 19.311724] bus_probe_device+0x94/0xa0
[ 19.311733] deferred_probe_work_func+0x80/0xb8
[ 19.311743] process_one_work+0x1e0/0x348
[ 19.311753] worker_thread+0x48/0x410
[ 19.311763] kthread+0xf4/0x110
[ 19.311771] ret_from_fork+0x10/0x20
[ 19.311782] freed by task 96 on cpu 10 at 19.285833s:
[ 19.311799] release_pcibus_dev+0x30/0x40
[ 19.311808] device_release+0x30/0x90
[ 19.311814] kobject_put+0xa8/0x120
[ 19.311832] device_unregister+0x20/0x30
[ 19.311839] pci_remove_bus+0x78/0x88
[ 19.311850] pci_remove_root_bus+0x5c/0x98
[ 19.311860] dw_pcie_host_deinit+0x28/0x78
[ 19.311866] tegra_pcie_deinit_controller+0x1c/0x38 [pcie_tegra194]
[ 19.311883] tegra_pcie_dw_probe+0x648/0xb28 [pcie_tegra194]
[ 19.311900] platform_probe+0x90/0xd8
[ 19.311906] really_probe+0xb8/0x298
[ 19.311916] __driver_probe_device+0x78/0xd8
[ 19.311926] driver_probe_device+0x38/0x120
[ 19.311936] __device_attach_driver+0x94/0xe0
[ 19.311947] bus_for_each_drv+0x70/0xc8
[ 19.311956] __device_attach+0xfc/0x188
[ 19.311966] device_initial_probe+0x10/0x18
[ 19.311976] bus_probe_device+0x94/0xa0
[ 19.311985] deferred_probe_work_func+0x80/0xb8
[ 19.311995] process_one_work+0x1e0/0x348
[ 19.312005] worker_thread+0x48/0x410
[ 19.312014] kthread+0xf4/0x110
[ 19.312022] ret_from_fork+0x10/0x20
[ 19.313579] CPU: 10 PID: 96 Comm: kworker/u24:2 Not tainted 6.2.0 #4
[ 19.320171] Hardware name: /, BIOS 1.0-d7fb19b 08/10/2022
[ 19.325852] Workqueue: events_unbound deferred_probe_work_func
[ 19.331919] ==================================================================
The stack trace is a bit misleading as dw_pcie_host_deinit() doesn't
directly call pci_bus_release_domain_nr(). The issue turns out to be in
pci_remove_root_bus() which first calls pci_remove_bus() which frees the
struct pci_bus when its struct device is released. Then
pci_bus_release_domain_nr() is called and accesses the freed
struct pci_bus. Reordering these fixes the issue.
Fixes: c14f7ccc9f5d ("PCI: Assign PCI domain IDs by ida_alloc()")
Reported-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Cc: Pali Rohár <pali@xxxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
---
drivers/pci/remove.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 0145aef1b930..22d39e12b236 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -157,8 +157,6 @@ void pci_remove_root_bus(struct pci_bus *bus)
list_for_each_entry_safe(child, tmp,
&bus->devices, bus_list)
pci_remove_bus_device(child);
- pci_remove_bus(bus);
- host_bridge->bus = NULL;
#ifdef CONFIG_PCI_DOMAINS_GENERIC
/* Release domain_nr if it was dynamically allocated */
@@ -166,6 +164,9 @@ void pci_remove_root_bus(struct pci_bus *bus)
pci_bus_release_domain_nr(bus, host_bridge->dev.parent);
#endif
+ pci_remove_bus(bus);
+ host_bridge->bus = NULL;
+
/* remove the host bridge */
device_del(&host_bridge->dev);
}
--
2.39.2