From: Yang Jihong <yangjihong1@huawei.com> mainline inclusion from mainline-v6.2-rc1 commit c1ac03af6ed45d05786c219d102f37eb44880f28 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I69283 CVE: NA -------------------------------- 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") Signed-off-by: Yang Jihong <yangjihong1@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Yang Jihong <yangjihong1@huawei.com> Reviewed-by: Zheng Yejian <zhengyejian1@huawei.com> Reviewed-by: Ye Weihua <yeweihua4@huawei.com> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com> --- kernel/trace/trace.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index feed30698280..9daaee7a9dd2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5771,7 +5771,20 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 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; } -- 2.25.1