CVE-2021-47441

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> mlxsw: thermal: Fix out-of-bounds memory accesses<br /> <br /> Currently, mlxsw allows cooling states to be set above the maximum<br /> cooling state supported by the driver:<br /> <br /> # cat /sys/class/thermal/thermal_zone2/cdev0/type<br /> mlxsw_fan<br /> # cat /sys/class/thermal/thermal_zone2/cdev0/max_state<br /> 10<br /> # echo 18 &gt; /sys/class/thermal/thermal_zone2/cdev0/cur_state<br /> # echo $?<br /> 0<br /> <br /> This results in out-of-bounds memory accesses when thermal state<br /> transition statistics are enabled (CONFIG_THERMAL_STATISTICS=y), as the<br /> transition table is accessed with a too large index (state) [1].<br /> <br /> According to the thermal maintainer, it is the responsibility of the<br /> driver to reject such operations [2].<br /> <br /> Therefore, return an error when the state to be set exceeds the maximum<br /> cooling state supported by the driver.<br /> <br /> To avoid dead code, as suggested by the thermal maintainer [3],<br /> partially revert commit a421ce088ac8 ("mlxsw: core: Extend cooling<br /> device with cooling levels") that tried to interpret these invalid<br /> cooling states (above the maximum) in a special way. The cooling levels<br /> array is not removed in order to prevent the fans going below 20% PWM,<br /> which would cause them to get stuck at 0% PWM.<br /> <br /> [1]<br /> BUG: KASAN: slab-out-of-bounds in thermal_cooling_device_stats_update+0x271/0x290<br /> Read of size 4 at addr ffff8881052f7bf8 by task kworker/0:0/5<br /> <br /> CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.15.0-rc3-custom-45935-gce1adf704b14 #122<br /> Hardware name: Mellanox Technologies Ltd. "MSN2410-CB2FO"/"SA000874", BIOS 4.6.5 03/08/2016<br /> Workqueue: events_freezable_power_ thermal_zone_device_check<br /> Call Trace:<br /> dump_stack_lvl+0x8b/0xb3<br /> print_address_description.constprop.0+0x1f/0x140<br /> kasan_report.cold+0x7f/0x11b<br /> thermal_cooling_device_stats_update+0x271/0x290<br /> __thermal_cdev_update+0x15e/0x4e0<br /> thermal_cdev_update+0x9f/0xe0<br /> step_wise_throttle+0x770/0xee0<br /> thermal_zone_device_update+0x3f6/0xdf0<br /> process_one_work+0xa42/0x1770<br /> worker_thread+0x62f/0x13e0<br /> kthread+0x3ee/0x4e0<br /> ret_from_fork+0x1f/0x30<br /> <br /> Allocated by task 1:<br /> kasan_save_stack+0x1b/0x40<br /> __kasan_kmalloc+0x7c/0x90<br /> thermal_cooling_device_setup_sysfs+0x153/0x2c0<br /> __thermal_cooling_device_register.part.0+0x25b/0x9c0<br /> thermal_cooling_device_register+0xb3/0x100<br /> mlxsw_thermal_init+0x5c5/0x7e0<br /> __mlxsw_core_bus_device_register+0xcb3/0x19c0<br /> mlxsw_core_bus_device_register+0x56/0xb0<br /> mlxsw_pci_probe+0x54f/0x710<br /> local_pci_probe+0xc6/0x170<br /> pci_device_probe+0x2b2/0x4d0<br /> really_probe+0x293/0xd10<br /> __driver_probe_device+0x2af/0x440<br /> driver_probe_device+0x51/0x1e0<br /> __driver_attach+0x21b/0x530<br /> bus_for_each_dev+0x14c/0x1d0<br /> bus_add_driver+0x3ac/0x650<br /> driver_register+0x241/0x3d0<br /> mlxsw_sp_module_init+0xa2/0x174<br /> do_one_initcall+0xee/0x5f0<br /> kernel_init_freeable+0x45a/0x4de<br /> kernel_init+0x1f/0x210<br /> ret_from_fork+0x1f/0x30<br /> <br /> The buggy address belongs to the object at ffff8881052f7800<br /> which belongs to the cache kmalloc-1k of size 1024<br /> The buggy address is located 1016 bytes inside of<br /> 1024-byte region [ffff8881052f7800, ffff8881052f7c00)<br /> The buggy address belongs to the page:<br /> page:0000000052355272 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1052f0<br /> head:0000000052355272 order:3 compound_mapcount:0 compound_pincount:0<br /> flags: 0x200000000010200(slab|head|node=0|zone=2)<br /> raw: 0200000000010200 ffffea0005034800 0000000300000003 ffff888100041dc0<br /> raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000<br /> page dumped because: kasan: bad access detected<br /> <br /> Memory state around the buggy address:<br /> ffff8881052f7a80: 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc fc<br /> ffff8881052f7b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc<br /> &gt;ffff8881052f7b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc<br /> ^<br /> ffff8881052f7c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc<br /> ffff8881052f7c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc<br /> <br /> [2] https://lore.kernel.org/linux-pm/9aca37cb-1629-5c67-<br /> ---truncated---