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| author | Yang Jihong <yangjihong1@huawei.com> | 2022-11-29 19:30:09 +0800 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2022-12-12 10:21:46 -0500 |
| commit | c1ac03af6ed45d05786c219d102f37eb44880f28 (patch) | |
| tree | a926435f077379e1951022abb05476330257055b /kernel | |
| parent | d358dfe60b7724ad0acb8cf8375a608b983e2b59 (diff) | |
| download | linux-stable-c1ac03af6ed45d05786c219d102f37eb44880f28.tar.gz linux-stable-c1ac03af6ed45d05786c219d102f37eb44880f28.tar.bz2 linux-stable-c1ac03af6ed45d05786c219d102f37eb44880f28.zip | |
tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line
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>
Diffstat (limited to 'kernel')
| -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 664619b3f1e1..548890c7c0f5 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6802,7 +6802,20 @@ 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; } |