Re: [PATCH v2] PCI: Assign PCI domain by ida_alloc()

From: Rob Herring
Date: Tue Mar 28 2023 - 09:32:25 EST

On Wed, Mar 22, 2023 at 9:36 AM Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
>
>
> On 21/03/2023 18:44, Jon Hunter wrote:
> >
> > On 20/03/2023 20:59, Pali Rohár wrote:
> >> Hello!
> >>
> >> On Monday 20 March 2023 20:26:05 Jon Hunter wrote:
> >>> Hi Pali,
> >>>
> >>> After this change was made we are seeing the following bug
> >>> report on a Tegra234 Jetson Orin board ...
> >>>
> >>> [ 17.172346] tegra194-pcie 141a0000.pcie: host bridge
> >>> /pcie@141a0000 ranges:
> >>> [ 17.172470] tegra194-pcie 141a0000.pcie: MEM
> >>> 0x2800000000..0x2b27ffffff -> 0x2800000000
> >>> [ 17.172519] tegra194-pcie 141a0000.pcie: MEM
> >>> 0x2b28000000..0x2b2fffffff -> 0x0040000000
> >>> [ 17.172548] tegra194-pcie 141a0000.pcie: IO
> >>> 0x003a100000..0x003a1fffff -> 0x003a100000
> >>> [ 17.173449] tegra194-pcie 141a0000.pcie: iATU: unroll T, 8 ob, 2
> >>> ib, align 64K, limit 32G
> >>> [ 18.279048] tegra194-pcie 141a0000.pcie: Phy link never came up
> >>> [ 19.279285] tegra194-pcie 141a0000.pcie: Phy link never came up
> >>> [ 19.279599] tegra194-pcie 141a0000.pcie: PCI host bridge to bus
> >>> 0005:00
> >>> [ 19.279613] pci_bus 0005:00: root bus resource [bus 00-ff]
> >>> [ 19.279622] pci_bus 0005:00: root bus resource [mem
> >>> 0x2800000000-0x2b27ffffff pref]
> >>> [ 19.279631] pci_bus 0005:00: root bus resource [mem
> >>> 0x2b28000000-0x2b2fffffff] (bus address [0x40000000-0x47ffffff])
> >>> [ 19.279639] pci_bus 0005:00: root bus resource [io
> >>> 0x200000-0x2fffff] (bus address [0x3a100000-0x3a1fffff])
> >>> [ 19.279687] pci 0005:00:00.0: [10de:229a] type 01 class 0x060400
> >>> [ 19.279886] pci 0005:00:00.0: PME# supported from D0 D3hot
> >>> [ 19.283256] pci 0005:00:00.0: PCI bridge to [bus 01-ff]
> >>> [ 19.283590] pcieport 0005:00:00.0: Adding to iommu group 26
> >>> [ 19.283991] pcieport 0005:00:00.0: PME: Signaling with IRQ 174
> >>> [ 19.284429] pcieport 0005:00:00.0: AER: enabled with IRQ 174
> >>> [ 19.285003] pci_bus 0005:01: busn_res: [bus 01-ff] is released
> >>> [ 19.285591] pci 0005:00:00.0: Removing from iommu group 26
> >>> [ 19.285751] pci_bus 0005:00: busn_res: [bus 00-ff] is released
> >>> [ 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
> >>
> >> Based on the above trace it looks like a double free of "pp->bridge"
> >> structure.
> >>
> >> Also, which kernel version are you using? Because from above third
> >> trace it looks like that dw_pcie_host_deinit() calls first
> >> pci_remove_root_bus() function and then (from first strace) it also
> >> calls pci_bus_release_domain_nr() function.

It's all the same stack trace. The struct pci_bus is a struct device
which is released first and then accessed by
of_pci_bus_release_domain_nr().

> > I have definitely seen this with v6.2. I was doing some more testing and
> > now it appears that the issue is somewhat intermittent. So now I am no
> > longer confident that reverting this change does fix it. The backtrace
> > made it seem like this is a likely candidate, but I need to do more
> > testing.
>
>
> OK, so I have done some more testing. I found that if I build the
> Tegra194 PCIe driver into the kernel, then I can reproduce the above
> 100%. I guess by loading early there is more chance of a probe deferral.
> With that I verified that the issue is seen on v6.2 (as I previously
> observed) and on v6.3-rc3. Reverting this commit on top of v6.3-rc3
> fixes this and I no longer see the problem.
>
> Let me know if you have any thoughts on how to fix this.

Does this fix it?:

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);
}