diff options
| author | Yang Jihong <yangjihong1@huawei.com> | 2022-11-29 19:30:09 +0800 |
|---|---|---|
| committer | Alexander Grund <flamefire89@gmail.com> | 2023-11-09 18:31:03 +0100 |
| commit | 9d0eb0082cdba627e720b12e9db80e5e3c884680 (patch) | |
| tree | 17e7f951cff8e874c7b2c88c937b1d1eefc3804a | |
| parent | f20831797b85895dc264e9bec339b77979cabfef (diff) | |
tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line
commit c1ac03af6ed45d05786c219d102f37eb44880f28 upstream.
print_trace_line may overflow seq_file buffer. If the event is not
consumed, the while loop keeps peeking this event, causing a infinite loop.
Link: https://lkml.kernel.org/r/20221129113009.182425-1-yangjihong1@huawei.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 088b1e427dbba ("ftrace: pipe fixes")
Change-Id: Ic7f41111b7c7944e9f64b010a3c1ff095c757b9d
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ulrich Hecht <uli+cip@fpond.eu>
| -rw-r--r-- | kernel/trace/trace.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 700995054081..fc4943ca95e2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4972,7 +4972,20 @@ waitagain: ret = print_trace_line(iter); if (ret == TRACE_TYPE_PARTIAL_LINE) { - /* don't print partial lines */ + /* + * If one print_trace_line() fills entire trace_seq in one shot, + * trace_seq_to_user() will returns -EBUSY because save_len == 0, + * In this case, we need to consume it, otherwise, loop will peek + * this event next time, resulting in an infinite loop. + */ + if (save_len == 0) { + iter->seq.full = 0; + trace_seq_puts(&iter->seq, "[LINE TOO BIG]\n"); + trace_consume(iter); + break; + } + + /* In other cases, don't print partial lines */ iter->seq.seq.len = save_len; break; } |