From: Ido Schimmel idosch@nvidia.com
commit 332fdf951df8b870e3da86b122ae304e2aabe88c upstream.
Currently, mlxsw allows cooling states to be set above the maximum cooling state supported by the driver:
# cat /sys/class/thermal/thermal_zone2/cdev0/type mlxsw_fan # cat /sys/class/thermal/thermal_zone2/cdev0/max_state 10 # echo 18 > /sys/class/thermal/thermal_zone2/cdev0/cur_state # echo $? 0
This results in out-of-bounds memory accesses when thermal state transition statistics are enabled (CONFIG_THERMAL_STATISTICS=y), as the transition table is accessed with a too large index (state) [1].
According to the thermal maintainer, it is the responsibility of the driver to reject such operations [2].
Therefore, return an error when the state to be set exceeds the maximum cooling state supported by the driver.
To avoid dead code, as suggested by the thermal maintainer [3], partially revert commit a421ce088ac8 ("mlxsw: core: Extend cooling device with cooling levels") that tried to interpret these invalid cooling states (above the maximum) in a special way. The cooling levels array is not removed in order to prevent the fans going below 20% PWM, which would cause them to get stuck at 0% PWM.
[1] BUG: KASAN: slab-out-of-bounds in thermal_cooling_device_stats_update+0x271/0x290 Read of size 4 at addr ffff8881052f7bf8 by task kworker/0:0/5
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.15.0-rc3-custom-45935-gce1adf704b14 #122 Hardware name: Mellanox Technologies Ltd. "MSN2410-CB2FO"/"SA000874", BIOS 4.6.5 03/08/2016 Workqueue: events_freezable_power_ thermal_zone_device_check Call Trace: dump_stack_lvl+0x8b/0xb3 print_address_description.constprop.0+0x1f/0x140 kasan_report.cold+0x7f/0x11b thermal_cooling_device_stats_update+0x271/0x290 __thermal_cdev_update+0x15e/0x4e0 thermal_cdev_update+0x9f/0xe0 step_wise_throttle+0x770/0xee0 thermal_zone_device_update+0x3f6/0xdf0 process_one_work+0xa42/0x1770 worker_thread+0x62f/0x13e0 kthread+0x3ee/0x4e0 ret_from_fork+0x1f/0x30
Allocated by task 1: kasan_save_stack+0x1b/0x40 __kasan_kmalloc+0x7c/0x90 thermal_cooling_device_setup_sysfs+0x153/0x2c0 __thermal_cooling_device_register.part.0+0x25b/0x9c0 thermal_cooling_device_register+0xb3/0x100 mlxsw_thermal_init+0x5c5/0x7e0 __mlxsw_core_bus_device_register+0xcb3/0x19c0 mlxsw_core_bus_device_register+0x56/0xb0 mlxsw_pci_probe+0x54f/0x710 local_pci_probe+0xc6/0x170 pci_device_probe+0x2b2/0x4d0 really_probe+0x293/0xd10 __driver_probe_device+0x2af/0x440 driver_probe_device+0x51/0x1e0 __driver_attach+0x21b/0x530 bus_for_each_dev+0x14c/0x1d0 bus_add_driver+0x3ac/0x650 driver_register+0x241/0x3d0 mlxsw_sp_module_init+0xa2/0x174 do_one_initcall+0xee/0x5f0 kernel_init_freeable+0x45a/0x4de kernel_init+0x1f/0x210 ret_from_fork+0x1f/0x30
The buggy address belongs to the object at ffff8881052f7800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 1016 bytes inside of 1024-byte region [ffff8881052f7800, ffff8881052f7c00) The buggy address belongs to the page: page:0000000052355272 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1052f0 head:0000000052355272 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x200000000010200(slab|head|node=0|zone=2) raw: 0200000000010200 ffffea0005034800 0000000300000003 ffff888100041dc0 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8881052f7a80: 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc fc ffff8881052f7b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881052f7b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^ ffff8881052f7c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881052f7c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[2] https://lore.kernel.org/linux-pm/9aca37cb-1629-5c67-1895-1fdc45c0244e@linaro... [3] https://lore.kernel.org/linux-pm/af9857f2-578e-de3a-e62b-6baff7e69fd4@linaro...
CC: Daniel Lezcano daniel.lezcano@linaro.org Fixes: a50c1e35650b ("mlxsw: core: Implement thermal zone") Fixes: a421ce088ac8 ("mlxsw: core: Extend cooling device with cooling levels") Signed-off-by: Ido Schimmel idosch@nvidia.com Tested-by: Vadim Pasternak vadimp@nvidia.com Link: https://lore.kernel.org/r/20211012174955.472928-1-idosch@idosch.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/mellanox/mlxsw/core_thermal.c | 52 ++------------------- 1 file changed, 5 insertions(+), 47 deletions(-)
--- a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c +++ b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c @@ -25,16 +25,8 @@ #define MLXSW_THERMAL_ZONE_MAX_NAME 16 #define MLXSW_THERMAL_TEMP_SCORE_MAX GENMASK(31, 0) #define MLXSW_THERMAL_MAX_STATE 10 +#define MLXSW_THERMAL_MIN_STATE 2 #define MLXSW_THERMAL_MAX_DUTY 255 -/* Minimum and maximum fan allowed speed in percent: from 20% to 100%. Values - * MLXSW_THERMAL_MAX_STATE + x, where x is between 2 and 10 are used for - * setting fan speed dynamic minimum. For example, if value is set to 14 (40%) - * cooling levels vector will be set to 4, 4, 4, 4, 4, 5, 6, 7, 8, 9, 10 to - * introduce PWM speed in percent: 40, 40, 40, 40, 40, 50, 60. 70, 80, 90, 100. - */ -#define MLXSW_THERMAL_SPEED_MIN (MLXSW_THERMAL_MAX_STATE + 2) -#define MLXSW_THERMAL_SPEED_MAX (MLXSW_THERMAL_MAX_STATE * 2) -#define MLXSW_THERMAL_SPEED_MIN_LEVEL 2 /* 20% */
/* External cooling devices, allowed for binding to mlxsw thermal zones. */ static char * const mlxsw_thermal_external_allowed_cdev[] = { @@ -635,49 +627,16 @@ static int mlxsw_thermal_set_cur_state(s struct mlxsw_thermal *thermal = cdev->devdata; struct device *dev = thermal->bus_info->dev; char mfsc_pl[MLXSW_REG_MFSC_LEN]; - unsigned long cur_state, i; int idx; - u8 duty; int err;
+ if (state > MLXSW_THERMAL_MAX_STATE) + return -EINVAL; + idx = mlxsw_get_cooling_device_idx(thermal, cdev); if (idx < 0) return idx;
- /* Verify if this request is for changing allowed fan dynamical - * minimum. If it is - update cooling levels accordingly and update - * state, if current state is below the newly requested minimum state. - * For example, if current state is 5, and minimal state is to be - * changed from 4 to 6, thermal->cooling_levels[0 to 5] will be changed - * all from 4 to 6. And state 5 (thermal->cooling_levels[4]) should be - * overwritten. - */ - if (state >= MLXSW_THERMAL_SPEED_MIN && - state <= MLXSW_THERMAL_SPEED_MAX) { - state -= MLXSW_THERMAL_MAX_STATE; - for (i = 0; i <= MLXSW_THERMAL_MAX_STATE; i++) - thermal->cooling_levels[i] = max(state, i); - - mlxsw_reg_mfsc_pack(mfsc_pl, idx, 0); - err = mlxsw_reg_query(thermal->core, MLXSW_REG(mfsc), mfsc_pl); - if (err) - return err; - - duty = mlxsw_reg_mfsc_pwm_duty_cycle_get(mfsc_pl); - cur_state = mlxsw_duty_to_state(duty); - - /* If current fan state is lower than requested dynamical - * minimum, increase fan speed up to dynamical minimum. - */ - if (state < cur_state) - return 0; - - state = cur_state; - } - - if (state > MLXSW_THERMAL_MAX_STATE) - return -EINVAL; - /* Normalize the state to the valid speed range. */ state = thermal->cooling_levels[state]; mlxsw_reg_mfsc_pack(mfsc_pl, idx, mlxsw_state_to_duty(state)); @@ -980,8 +939,7 @@ int mlxsw_thermal_init(struct mlxsw_core
/* Initialize cooling levels per PWM state. */ for (i = 0; i < MLXSW_THERMAL_MAX_STATE; i++) - thermal->cooling_levels[i] = max(MLXSW_THERMAL_SPEED_MIN_LEVEL, - i); + thermal->cooling_levels[i] = max(MLXSW_THERMAL_MIN_STATE, i);
thermal->polling_delay = bus_info->low_frequency ? MLXSW_THERMAL_SLOW_POLL_INT :