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Message-ID: <YCOAy8S4FI8CPr59@kroah.com>
Date: Wed, 10 Feb 2021 07:44:27 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Dave Jiang <dave.jiang@...el.com>
Cc: Jacob Pan <jacob.jun.pan@...el.com>,
Dave Ertman <david.m.ertman@...el.com>,
Dan Williams <dan.j.williams@...el.com>, rafael@...nel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] driver core: auxiliary bus: Fix calling stage for
auxiliary bus init
On Tue, Feb 09, 2021 at 03:17:00PM -0700, Dave Jiang wrote:
> When the auxiliary device code is built into the kernel, it can be executed
> before the auxiliary bus is registered. This causes bus->p to be not
> allocated and triggers a NULL pointer dereference when the auxiliary bus
> device gets added with bus_add_device(). Call the auxiliary_bus_init()
> under driver_init() so the bus is initialized before devices.
>
> Below is the kernel splat for the bug:
> [ 1.948215] BUG: kernel NULL pointer dereference, address: 0000000000000060
> [ 1.950670] #PF: supervisor read access in kernel mode
> [ 1.950670] #PF: error_code(0x0000) - not-present page
> [ 1.950670] PGD 0
> [ 1.950670] Oops: 0000 1 SMP NOPTI
> [ 1.950670] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.10.0-intel-nextsvmtest+ #2205
> [ 1.950670] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
> [ 1.950670] RIP: 0010:bus_add_device+0x64/0x140
> [ 1.950670] Code: 00 49 8b 75 20 48 89 df e8 59 a1 ff ff 41 89 c4 85 c0 75 7b 48 8b 53 50 48 85 d2 75 03 48 8b 13 49 8b 85 a0 00 00 00 48 89 de <48> 8
> 78 60 48 83 c7 18 e8 ef d9 a9 ff 41 89 c4 85 c0 75 45 48 8b
> [ 1.950670] RSP: 0000:ff46032ac001baf8 EFLAGS: 00010246
> [ 1.950670] RAX: 0000000000000000 RBX: ff4597f7414aa680 RCX: 0000000000000000
> [ 1.950670] RDX: ff4597f74142bbc0 RSI: ff4597f7414aa680 RDI: ff4597f7414aa680
> [ 1.950670] RBP: ff46032ac001bb10 R08: 0000000000000044 R09: 0000000000000228
> [ 1.950670] R10: ff4597f741141b30 R11: ff4597f740182a90 R12: 0000000000000000
> [ 1.950670] R13: ffffffffa5e936c0 R14: 0000000000000000 R15: 0000000000000000
> [ 1.950670] FS: 0000000000000000(0000) GS:ff4597f7bba00000(0000) knlGS:0000000000000000
> [ 1.950670] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1.950670] CR2: 0000000000000060 CR3: 000000002140c001 CR4: 0000000000f71ef0
> [ 1.950670] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 1.950670] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
> [ 1.950670] PKRU: 55555554
> [ 1.950670] Call Trace:
> [ 1.950670] device_add+0x3ee/0x850
> [ 1.950670] __auxiliary_device_add+0x47/0x60
> [ 1.950670] idxd_pci_probe+0xf77/0x1180
> [ 1.950670] local_pci_probe+0x4a/0x90
> [ 1.950670] pci_device_probe+0xff/0x1b0
> [ 1.950670] really_probe+0x1cf/0x440
> [ 1.950670] ? rdinit_setup+0x31/0x31
> [ 1.950670] driver_probe_device+0xe8/0x150
> [ 1.950670] device_driver_attach+0x58/0x60
> [ 1.950670] __driver_attach+0x8f/0x150
> [ 1.950670] ? device_driver_attach+0x60/0x60
> [ 1.950670] ? device_driver_attach+0x60/0x60
> [ 1.950670] bus_for_each_dev+0x79/0xc0
> [ 1.950670] ? kmem_cache_alloc_trace+0x323/0x430
> [ 1.950670] driver_attach+0x1e/0x20
> [ 1.950670] bus_add_driver+0x154/0x1f0
> [ 1.950670] driver_register+0x70/0xc0
> [ 1.950670] __pci_register_driver+0x54/0x60
> [ 1.950670] idxd_init_module+0xe2/0xfc
> [ 1.950670] ? idma64_platform_driver_init+0x19/0x19
> [ 1.950670] do_one_initcall+0x4a/0x1e0
> [ 1.950670] kernel_init_freeable+0x1fc/0x25c
> [ 1.950670] ? rest_init+0xba/0xba
> [ 1.950670] kernel_init+0xe/0x116
> [ 1.950670] ret_from_fork+0x1f/0x30
> [ 1.950670] Modules linked in:
> [ 1.950670] CR2: 0000000000000060
> [ 1.950670] --[ end trace cd7d1b226d3ca901 ]--
>
> Fixes: 7de3697e9cbd ("Add auxiliary bus support")
> Reported-by: Jacob Pan <jacob.jun.pan@...el.com>
> Acked-by: Dave Ertman <david.m.ertman@...el.com>
> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Dave Jiang <dave.jiang@...el.com>
> ---
>
> v2:
> - Call in driver_init() to ensure aux bus gets init before devices. (GregKH)
>
> drivers/base/auxiliary.c | 10 +---------
> drivers/base/base.h | 5 +++++
> drivers/base/init.c | 1 +
> 3 files changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/base/auxiliary.c b/drivers/base/auxiliary.c
> index 8336535f1e11..8ff389653126 100644
> --- a/drivers/base/auxiliary.c
> +++ b/drivers/base/auxiliary.c
> @@ -260,19 +260,11 @@ void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv)
> }
> EXPORT_SYMBOL_GPL(auxiliary_driver_unregister);
>
> -static int __init auxiliary_bus_init(void)
> +int __init auxiliary_bus_init(void)
> {
> return bus_register(&auxiliary_bus_type);
Ok, you return an int, and then...
> }
>
> -static void __exit auxiliary_bus_exit(void)
> -{
> - bus_unregister(&auxiliary_bus_type);
> -}
> -
> -module_init(auxiliary_bus_init);
> -module_exit(auxiliary_bus_exit);
> -
> MODULE_LICENSE("GPL v2");
> MODULE_DESCRIPTION("Auxiliary Bus");
> MODULE_AUTHOR("David Ertman <david.m.ertman@...el.com>");
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index f5600a83124f..978ad265c42e 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -119,6 +119,11 @@ static inline int hypervisor_init(void) { return 0; }
> extern int platform_bus_init(void);
> extern void cpu_dev_init(void);
> extern void container_dev_init(void);
> +#ifdef CONFIG_AUXILIARY_BUS
> +extern int auxiliary_bus_init(void);
> +#else
> +static inline int auxiliary_bus_init(void) { return 0; }
> +#endif
>
> struct kobject *virtual_device_parent(struct device *dev);
>
> diff --git a/drivers/base/init.c b/drivers/base/init.c
> index 908e6520e804..a9f57c22fb9e 100644
> --- a/drivers/base/init.c
> +++ b/drivers/base/init.c
> @@ -32,6 +32,7 @@ void __init driver_init(void)
> */
> of_core_init();
> platform_bus_init();
> + auxiliary_bus_init();
Ignore it :(
Please just make the function not return anything.
thanks,
greg k-h
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