This is a note to let you know that I've just added the patch titled
audit: fix possible soft lockup in __audit_inode_child()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
audit-fix-possible-soft-lockup-in-__audit_inode_chil.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f6b3b7d7e35076b615f4398fdfaf285d4e61eb34
Author: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx>
Date: Tue Aug 8 20:14:35 2023 +0800
audit: fix possible soft lockup in __audit_inode_child()
[ Upstream commit b59bc6e37237e37eadf50cd5de369e913f524463 ]
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.
Fixes: 5195d8e217a7 ("audit: dynamically allocate audit_names when not enough space is in the names array")
Signed-off-by: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx>
Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index e8e90c0c49367..fc4223f30e847 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2161,6 +2161,8 @@ void __audit_inode_child(struct inode *parent,
}
}
+ cond_resched();
+
/* is there a matching child entry? */
list_for_each_entry(n, &context->names_list, list) {
/* can only match entries that have a name */
