This is a note to let you know that I've just added the patch titled

driver core: auxiliary bus: Fix calling stage for auxiliary bus init

to my driver-core git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git in the driver-core-next branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

From 471b12c43f376d5203dbff0e91316eea11f6f4df Mon Sep 17 00:00:00 2001

From: Dave Jiang dave.jiang@intel.com Date: Wed, 10 Feb 2021 13:16:11 -0700 Subject: driver core: auxiliary bus: Fix calling stage for auxiliary bus init

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@intel.com Reviewed-by: Dan Williams dan.j.williams@intel.com Acked-by: Dave Ertman david.m.ertman@intel.com Signed-off-by: Dave Jiang dave.jiang@intel.com Link: https://lore.kernel.org/r/20210210201611.1611074-1-dave.jiang@intel.com Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/base/auxiliary.c | 13 +++---------- drivers/base/base.h | 5 +++++ drivers/base/init.c | 1 + 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/base/auxiliary.c b/drivers/base/auxiliary.c index 8336535f1e11..d8b314e7d0fd 100644 --- a/drivers/base/auxiliary.c +++ b/drivers/base/auxiliary.c @@ -15,6 +15,7 @@ #include <linux/pm_runtime.h> #include <linux/string.h> #include <linux/auxiliary_bus.h> +#include "base.h"

static const struct auxiliary_device_id *auxiliary_match_id(const struct auxiliary_device_id *id, const struct auxiliary_device *auxdev) @@ -260,19 +261,11 @@ void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv) } EXPORT_SYMBOL_GPL(auxiliary_driver_unregister);

-static int __init auxiliary_bus_init(void) +void __init auxiliary_bus_init(void) { - return bus_register(&auxiliary_bus_type); + WARN_ON(bus_register(&auxiliary_bus_type)); }

-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@intel.com"); diff --git a/drivers/base/base.h b/drivers/base/base.h index f5600a83124f..52b3d7b75c27 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 void auxiliary_bus_init(void); +#else +static inline void auxiliary_bus_init(void) { } +#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(); cpu_dev_init(); memory_dev_init(); container_dev_init();