[PATCH 5.7 103/112] drm/amd/powerplay: Fix NULL dereference in lock_bus() on Vega20 w/o RAS

Greg Kroah-Hartman
2020-07-07T15:28:03Z

From: Ivan Mironov <mironov.ivan@gmail.com>

commit 7e89e4aaa9ae83107d059c186955484b3aa6eb23 upstream.

I updated my system with Radeon VII from kernel 5.6 to kernel 5.7, and
following started to happen on each boot:

...
BUG: kernel NULL pointer dereference, address: 0000000000000128
...
CPU: 9 PID: 1940 Comm: modprobe Tainted: G E 5.7.2-200.im0.fc32.x86_64 #1
Hardware name: System manufacturer System Product Name/PRIME X570-P, BIOS 1407 04/02/2020
RIP: 0010:lock_bus+0x42/0x60 [amdgpu]
...
Call Trace:
i2c_smbus_xfer+0x3d/0xf0
i2c_default_probe+0xf3/0x130
i2c_detect.isra.0+0xfe/0x2b0
? kfree+0xa3/0x200
? kobject_uevent_env+0x11f/0x6a0
? i2c_detect.isra.0+0x2b0/0x2b0
__process_new_driver+0x1b/0x20
bus_for_each_dev+0x64/0x90
? 0xffffffffc0f34000
i2c_register_driver+0x73/0xc0
do_one_initcall+0x46/0x200
? _cond_resched+0x16/0x40
? kmem_cache_alloc_trace+0x167/0x220
? do_init_module+0x23/0x260
do_init_module+0x5c/0x260
__do_sys_init_module+0x14f/0x170
do_syscall_64+0x5b/0xf0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
...

Error appears when some i2c device driver tries to probe for devices
using adapter registered by `smu_v11_0_i2c_eeprom_control_init()`.
Code supporting this adapter requires `adev->psp.ras.ras` to be not
NULL, which is true only when `amdgpu_ras_init()` detects HW support by
calling `amdgpu_ras_check_supported()`.

Before 9015d60c9ee1, adapter was registered by

-> amdgpu_device_ip_init()
-> amdgpu_ras_recovery_init()
-> amdgpu_ras_eeprom_init()
-> smu_v11_0_i2c_eeprom_control_init()

after verifying that `adev->psp.ras.ras` is not NULL in
`amdgpu_ras_recovery_init()`. Currently it is registered
unconditionally by

-> amdgpu_device_ip_init()
-> pp_sw_init()
-> hwmgr_sw_init()
-> vega20_smu_init()
-> smu_v11_0_i2c_eeprom_control_init()

Fix simply adds HW support check (ras == NULL => no support) before
calling `smu_v11_0_i2c_eeprom_control_{init,fini}()`.

Please note that there is a chance that similar fix is also required for
CHIP_ARCTURUS. I do not know whether any actual Arcturus hardware without
RAS exist, and whether calling `smu_i2c_eeprom_init()` makes any sense
when there is no HW support.

Cc: stable@vger.kernel.org
Fixes: 9015d60c9ee1 ("drm/amdgpu: Move EEPROM I2C adapter to amdgpu_device")
Signed-off-by: Ivan Mironov <mironov.ivan@gmail.com>
Tested-by: Bjorn Nostvold <bjorn.nostvold@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/amd/powerplay/smumgr/vega20_smumgr.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/amd/powerplay/smumgr/vega20_smumgr.c
+++ b/drivers/gpu/drm/amd/powerplay/smumgr/vega20_smumgr.c
@@ -508,9 +508,11 @@ static int vega20_smu_init(struct pp_hwm
priv->smu_tables.entry[TABLE_ACTIVITY_MONITOR_COEFF].version = 0x01;
priv->smu_tables.entry[TABLE_ACTIVITY_MONITOR_COEFF].size = sizeof(DpmActivityMonitorCoeffInt_t);

- ret = smu_v11_0_i2c_eeprom_control_init(&adev->pm.smu_i2c);
- if (ret)
- goto err4;
+ if (adev->psp.ras.ras) {
+ ret = smu_v11_0_i2c_eeprom_control_init(&adev->pm.smu_i2c);
+ if (ret)
+ goto err4;
+ }

return 0;

@@ -546,7 +548,8 @@ static int vega20_smu_fini(struct pp_hwm
(struct vega20_smumgr *)(hwmgr->smu_backend);
struct amdgpu_device *adev = hwmgr->adev;

- smu_v11_0_i2c_eeprom_control_fini(&adev->pm.smu_i2c);
+ if (adev->psp.ras.ras)
+ smu_v11_0_i2c_eeprom_control_fini(&adev->pm.smu_i2c);

if (priv) {
amdgpu_bo_free_kernel(&priv->smu_tables.entry[TABLE_PPTABLE].handle,