CVE-2022-50491: linux kernel vulnerability

What is known

In the Linux kernel, the following vulnerability has been resolved: coresight: cti: Fix hang in cti_disable_hw() cti_enable_hw() and cti_disable_hw() are called from an atomic context so shouldn't use runtime PM because it can result in a sleep when communicating with firmware. Since commit 3c6656337852 ("Revert "firmware: arm_scmi: Add clock management to the SCMI power domain""), this causes a hang on Juno when running the Perf Coresight tests or running this command: perf record -e cs_etm//u -- ls This was also missed until the revert commit because pm_runtime_put() was called with the wrong device until commit 692c9a499b28 ("coresight: cti: Correct the parameter for pm_runtime_put") With lock and scheduler debugging enabled the following is output: coresight cti_sys0: cti_enable_hw -- dev:cti_sys0 parent: 20020000.cti BUG: sleeping function called from invalid context at drivers/base/power/runtime.c:1151 in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 330, name: perf-exec preempt_count: 2, expected: 0 RCU nest depth: 0, expected: 0 INFO: lockdep is turned off. irq event stamp: 0 hardirqs last enabled at (0): [<0000000000000000>] 0x0 hardirqs last disabled at (0): [<ffff80000822b394>] copy_process+0xa0c/0x1948 softirqs last enabled at (0): [<ffff80000822b394>] copy_process+0xa0c/0x1948 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 3 PID: 330 Comm: perf-exec Not tainted 6.0.0-00053-g042116d99298 #7 Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Sep 13 2022 Call trace: dump_backtrace+0x134/0x140 show_stack+0x20/0x58 dump_stack_lvl+0x8c/0xb8 dump_stack+0x18/0x34 __might_resched+0x180/0x228 __might_sleep+0x50/0x88 __pm_runtime_resume+0xac/0xb0 cti_enable+0x44/0x120 coresight_control_assoc_ectdev+0xc0/0x150 coresight_enable_path+0xb4/0x288 etm_event_start+0x138/0x170 etm_event_add+0x48/0x70 event_sched_in.isra.122+0xb4/0x280 merge_sched_in+0x1fc/0x3d0 visit_groups_merge.constprop.137+0x16c/0x4b0 ctx_sched_in+0x114/0x1f0 perf_event_sched_in+0x60/0x90 ctx_resched+0x68/0xb0 perf_event_exec+0x138/0x508 begin_new_exec+0x52c/0xd40 load_elf_binary+0x6b8/0x17d0 bprm_execve+0x360/0x7f8 do_execveat_common.isra.47+0x218/0x238 __arm64_sys_execve+0x48/0x60 invoke_syscall+0x4c/0x110 el0_svc_common.constprop.4+0xfc/0x120 do_el0_svc+0x34/0xc0 el0_svc+0x40/0x98 el0t_64_sync_handler+0x98/0xc0 el0t_64_sync+0x170/0x174 Fix the issue by removing the runtime PM calls completely. They are not needed here because it must have already been done when building the path for a trace. [ Fix build warnings ]

Business impact

Successful exploitation of CVE-2022-50491, a medium vulnerability (CVSS 5.5) affecting linux kernel, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether linux kernel is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

• NVD
• Reference
• Reference
• Reference
• Reference