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d1776c0202
The filter string doesn't get freed when a dynamic event is deleted. If a
filter is set, then memory is leaked:
root@localhost:/sys/kernel/tracing# echo 'e:egroup/stat_runtime_4core \
sched/sched_stat_runtime runtime=$runtime:u32 if cpu < 4' >> dynamic_events
root@localhost:/sys/kernel/tracing# echo "-:egroup/stat_runtime_4core" >> dynamic_events
root@localhost:/sys/kernel/tracing# echo scan > /sys/kernel/debug/kmemleak
[ 224.416373] kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
root@localhost:/sys/kernel/tracing# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff88810156f1b8 (size 8):
comm "bash", pid 224, jiffies 4294935612 (age 55.800s)
hex dump (first 8 bytes):
63 70 75 20 3c 20 34 00 cpu < 4.
backtrace:
[<000000009f880725>] __kmem_cache_alloc_node+0x18e/0x720
[<0000000042492946>] __kmalloc+0x57/0x240
[<0000000034ea7995>] __trace_eprobe_create+0x1214/0x1d30
[<00000000d70ef730>] trace_probe_create+0xf6/0x110
[<00000000915c7b16>] eprobe_dyn_event_create+0x21/0x30
[<000000000d894386>] create_dyn_event+0xf3/0x1a0
[<00000000e9af57d5>] trace_parse_run_command+0x1a9/0x2e0
[<0000000080777f18>] dyn_event_write+0x39/0x50
[<0000000089f0ec73>] vfs_write+0x311/0xe50
[<000000003da1bdda>] ksys_write+0x158/0x2a0
[<00000000bb1e616e>] __x64_sys_write+0x7c/0xc0
[<00000000e8aef1f7>] do_syscall_64+0x60/0x90
[<00000000fe7fe8ba>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
Additionally, in __trace_eprobe_create() function, if an error occurs after
the call to trace_eprobe_parse_filter(), which allocates the filter string,
then memory is also leaked. That can be reproduced by creating the same
event probe twice:
root@localhost:/sys/kernel/tracing# echo 'e:egroup/stat_runtime_4core \
sched/sched_stat_runtime runtime=$runtime:u32 if cpu < 4' >> dynamic_events
root@localhost:/sys/kernel/tracing# echo 'e:egroup/stat_runtime_4core \
sched/sched_stat_runtime runtime=$runtime:u32 if cpu < 4' >> dynamic_events
-bash: echo: write error: File exists
root@localhost:/sys/kernel/tracing# echo scan > /sys/kernel/debug/kmemleak
[ 207.871584] kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
root@localhost:/sys/kernel/tracing# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff8881020d17a8 (size 8):
comm "bash", pid 223, jiffies 4294938308 (age 31.000s)
hex dump (first 8 bytes):
63 70 75 20 3c 20 34 00 cpu < 4.
backtrace:
[<000000000e4f5f31>] __kmem_cache_alloc_node+0x18e/0x720
[<0000000024f0534b>] __kmalloc+0x57/0x240
[<000000002930a28e>] __trace_eprobe_create+0x1214/0x1d30
[<0000000028387903>] trace_probe_create+0xf6/0x110
[<00000000a80d6a9f>] eprobe_dyn_event_create+0x21/0x30
[<000000007168698c>] create_dyn_event+0xf3/0x1a0
[<00000000f036bf6a>] trace_parse_run_command+0x1a9/0x2e0
[<00000000014bde8b>] dyn_event_write+0x39/0x50
[<0000000078a097f7>] vfs_write+0x311/0xe50
[<00000000996cb208>] ksys_write+0x158/0x2a0
[<00000000a3c2acb0>] __x64_sys_write+0x7c/0xc0
[<0000000006b5d698>] do_syscall_64+0x60/0x90
[<00000000780e8ecf>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fix both issues by releasing the filter string in
trace_event_probe_cleanup().
Link: https://lore.kernel.org/all/20221108235738.1021467-1-rafaelmendsr@gmail.com/
Fixes:
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.. | ||
bpf | ||
cgroup | ||
configs | ||
debug | ||
dma | ||
entry | ||
events | ||
futex | ||
gcov | ||
irq | ||
kcsan | ||
livepatch | ||
locking | ||
module | ||
power | ||
printk | ||
rcu | ||
sched | ||
time | ||
trace | ||
.gitignore | ||
acct.c | ||
async.c | ||
audit_fsnotify.c | ||
audit_tree.c | ||
audit_watch.c | ||
audit.c | ||
audit.h | ||
auditfilter.c | ||
auditsc.c | ||
backtracetest.c | ||
bounds.c | ||
capability.c | ||
cfi.c | ||
compat.c | ||
configs.c | ||
context_tracking.c | ||
cpu_pm.c | ||
cpu.c | ||
crash_core.c | ||
crash_dump.c | ||
cred.c | ||
delayacct.c | ||
dma.c | ||
exec_domain.c | ||
exit.c | ||
extable.c | ||
fail_function.c | ||
fork.c | ||
freezer.c | ||
gen_kheaders.sh | ||
groups.c | ||
hung_task.c | ||
iomem.c | ||
irq_work.c | ||
jump_label.c | ||
kallsyms_internal.h | ||
kallsyms.c | ||
kcmp.c | ||
Kconfig.freezer | ||
Kconfig.hz | ||
Kconfig.locks | ||
Kconfig.preempt | ||
kcov.c | ||
kexec_core.c | ||
kexec_elf.c | ||
kexec_file.c | ||
kexec_internal.h | ||
kexec.c | ||
kheaders.c | ||
kmod.c | ||
kprobes.c | ||
ksysfs.c | ||
kthread.c | ||
latencytop.c | ||
Makefile | ||
module_signature.c | ||
notifier.c | ||
nsproxy.c | ||
padata.c | ||
panic.c | ||
params.c | ||
pid_namespace.c | ||
pid.c | ||
profile.c | ||
ptrace.c | ||
range.c | ||
reboot.c | ||
regset.c | ||
relay.c | ||
resource_kunit.c | ||
resource.c | ||
rseq.c | ||
scftorture.c | ||
scs.c | ||
seccomp.c | ||
signal.c | ||
smp.c | ||
smpboot.c | ||
smpboot.h | ||
softirq.c | ||
stackleak.c | ||
stacktrace.c | ||
static_call_inline.c | ||
static_call.c | ||
stop_machine.c | ||
sys_ni.c | ||
sys.c | ||
sysctl-test.c | ||
sysctl.c | ||
task_work.c | ||
taskstats.c | ||
torture.c | ||
tracepoint.c | ||
tsacct.c | ||
ucount.c | ||
uid16.c | ||
uid16.h | ||
umh.c | ||
up.c | ||
user_namespace.c | ||
user-return-notifier.c | ||
user.c | ||
usermode_driver.c | ||
utsname_sysctl.c | ||
utsname.c | ||
watch_queue.c | ||
watchdog_hld.c | ||
watchdog.c | ||
workqueue_internal.h | ||
workqueue.c |