Description

In the Linux kernel, the following vulnerability has been resolved: audit: fix possible soft lockup in __audit_inode_child() Tracefs or debugfs maybe cause hundreds to thousands of PATH records, too many PATH records maybe cause soft lockup. For example: 1. CONFIG_KASAN=y && CONFIG_PREEMPTION=n 2. auditctl -a exit,always -S open -k key 3. sysctl -w kernel.watchdog_thresh=5 4. mkdir /sys/kernel/debug/tracing/instances/test There may be a soft lockup as follows: watchdog: BUG: soft lockup - CPU#45 stuck for 7s! [mkdir:15498] Kernel panic - not syncing: softlockup: hung tasks Call trace: dump_backtrace+0x0/0x30c show_stack+0x20/0x30 dump_stack+0x11c/0x174 panic+0x27c/0x494 watchdog_timer_fn+0x2bc/0x390 __run_hrtimer+0x148/0x4fc __hrtimer_run_queues+0x154/0x210 hrtimer_interrupt+0x2c4/0x760 arch_timer_handler_phys+0x48/0x60 handle_percpu_devid_irq+0xe0/0x340 __handle_domain_irq+0xbc/0x130 gic_handle_irq+0x78/0x460 el1_irq+0xb8/0x140 __audit_inode_child+0x240/0x7bc tracefs_create_file+0x1b8/0x2a0 trace_create_file+0x18/0x50 event_create_dir+0x204/0x30c __trace_add_new_event+0xac/0x100 event_trace_add_tracer+0xa0/0x130 trace_array_create_dir+0x60/0x140 trace_array_create+0x1e0/0x370 instance_mkdir+0x90/0xd0 tracefs_syscall_mkdir+0x68/0xa0 vfs_mkdir+0x21c/0x34c do_mkdirat+0x1b4/0x1d4 __arm64_sys_mkdirat+0x4c/0x60 el0_svc_common.constprop.0+0xa8/0x240 do_el0_svc+0x8c/0xc0 el0_svc+0x20/0x30 el0_sync_handler+0xb0/0xb4 el0_sync+0x160/0x180 Therefore, we add cond_resched() to __audit_inode_child() to fix it.

References 9

• git.kernel.org https://git.kernel.org/stable/c/0152e7758cc4e9f8bfba8dbea4438d8e488d6c08
• git.kernel.org https://git.kernel.org/stable/c/1640c7bd4eddec6c72f3a99cbb74e333a2ce9f5d
• git.kernel.org https://git.kernel.org/stable/c/8a40b491372966ba5426e138a53460985565d5a6
• git.kernel.org https://git.kernel.org/stable/c/8e76b944a7b9bddef190ffe2e29c9ae342ab91ed
• git.kernel.org https://git.kernel.org/stable/c/98ef243d5900d75a64539a2165745bffbb155d43
• git.kernel.org https://git.kernel.org/stable/c/9ca08adb75fb40a8f742c371927ee73f9dc753bf
• git.kernel.org https://git.kernel.org/stable/c/b59bc6e37237e37eadf50cd5de369e913f524463
• git.kernel.org https://git.kernel.org/stable/c/d061e2bfc20f2914656385816e0d20566213c54c
• git.kernel.org https://git.kernel.org/stable/c/f6364fa751d7486502c777f124a14d4d543fc5eb

Remediation