diff options
author | Zheng Yejian <zhengyejian1@huawei.com> | 2023-08-17 15:55:39 +0300 |
---|---|---|
committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2023-08-17 20:49:37 +0300 |
commit | eecb91b9f98d6427d4af5fdb8f108f52572a39e7 (patch) | |
tree | 264c941c84c1059df7821451a26117e65cfecaa6 /kernel/trace | |
parent | c4d6b5438116c184027b2e911c0f2c7c406fb47c (diff) | |
download | linux-eecb91b9f98d6427d4af5fdb8f108f52572a39e7.tar.xz |
tracing: Fix memleak due to race between current_tracer and trace
Kmemleak report a leak in graph_trace_open():
unreferenced object 0xffff0040b95f4a00 (size 128):
comm "cat", pid 204981, jiffies 4301155872 (age 99771.964s)
hex dump (first 32 bytes):
e0 05 e7 b4 ab 7d 00 00 0b 00 01 00 00 00 00 00 .....}..........
f4 00 01 10 00 a0 ff ff 00 00 00 00 65 00 10 00 ............e...
backtrace:
[<000000005db27c8b>] kmem_cache_alloc_trace+0x348/0x5f0
[<000000007df90faa>] graph_trace_open+0xb0/0x344
[<00000000737524cd>] __tracing_open+0x450/0xb10
[<0000000098043327>] tracing_open+0x1a0/0x2a0
[<00000000291c3876>] do_dentry_open+0x3c0/0xdc0
[<000000004015bcd6>] vfs_open+0x98/0xd0
[<000000002b5f60c9>] do_open+0x520/0x8d0
[<00000000376c7820>] path_openat+0x1c0/0x3e0
[<00000000336a54b5>] do_filp_open+0x14c/0x324
[<000000002802df13>] do_sys_openat2+0x2c4/0x530
[<0000000094eea458>] __arm64_sys_openat+0x130/0x1c4
[<00000000a71d7881>] el0_svc_common.constprop.0+0xfc/0x394
[<00000000313647bf>] do_el0_svc+0xac/0xec
[<000000002ef1c651>] el0_svc+0x20/0x30
[<000000002fd4692a>] el0_sync_handler+0xb0/0xb4
[<000000000c309c35>] el0_sync+0x160/0x180
The root cause is descripted as follows:
__tracing_open() { // 1. File 'trace' is being opened;
...
*iter->trace = *tr->current_trace; // 2. Tracer 'function_graph' is
// currently set;
...
iter->trace->open(iter); // 3. Call graph_trace_open() here,
// and memory are allocated in it;
...
}
s_start() { // 4. The opened file is being read;
...
*iter->trace = *tr->current_trace; // 5. If tracer is switched to
// 'nop' or others, then memory
// in step 3 are leaked!!!
...
}
To fix it, in s_start(), close tracer before switching then reopen the
new tracer after switching. And some tracers like 'wakeup' may not update
'iter->private' in some cases when reopen, then it should be cleared
to avoid being mistakenly closed again.
Link: https://lore.kernel.org/linux-trace-kernel/20230817125539.1646321-1-zhengyejian1@huawei.com
Fixes: d7350c3f4569 ("tracing/core: make the read callbacks reentrants")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r-- | kernel/trace/trace.c | 9 | ||||
-rw-r--r-- | kernel/trace/trace_irqsoff.c | 3 | ||||
-rw-r--r-- | kernel/trace/trace_sched_wakeup.c | 2 |
3 files changed, 12 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b0e8eb6ea8ac..29a2e4d7886d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4213,8 +4213,15 @@ static void *s_start(struct seq_file *m, loff_t *pos) * will point to the same string as current_trace->name. */ mutex_lock(&trace_types_lock); - if (unlikely(tr->current_trace && iter->trace->name != tr->current_trace->name)) + if (unlikely(tr->current_trace && iter->trace->name != tr->current_trace->name)) { + /* Close iter->trace before switching to the new current tracer */ + if (iter->trace->close) + iter->trace->close(iter); *iter->trace = *tr->current_trace; + /* Reopen the new current tracer */ + if (iter->trace->open) + iter->trace->open(iter); + } mutex_unlock(&trace_types_lock); #ifdef CONFIG_TRACER_MAX_TRACE diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index 590b3d51afae..ba37f768e2f2 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -231,7 +231,8 @@ static void irqsoff_trace_open(struct trace_iterator *iter) { if (is_graph(iter->tr)) graph_trace_open(iter); - + else + iter->private = NULL; } static void irqsoff_trace_close(struct trace_iterator *iter) diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 330aee1c1a49..0469a04a355f 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -168,6 +168,8 @@ static void wakeup_trace_open(struct trace_iterator *iter) { if (is_graph(iter->tr)) graph_trace_open(iter); + else + iter->private = NULL; } static void wakeup_trace_close(struct trace_iterator *iter) |