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| author |   Nikita Yushchenko <nikita.yushchenko@virtuozzo.com> | 2021-11-18 17:55:16 +0300 |
|---|---|---|
| committer |   Steven Rostedt (VMware) <rostedt@goodmis.org> | 2021-11-18 21:10:18 -0500 |
| commit | 2ef75e9bd2c998f1c6f6f23a3744136105ddefd5 (patch) | |
| tree | 4d410a3f4373de3ddd33f137f1f3a8d94609e2c3 /kernel/trace/trace.c | |
| parent | tracing: Use memset_startat() to zero struct trace_iterator (diff) | |
| download | linux-dev-2ef75e9bd2c998f1c6f6f23a3744136105ddefd5.tar.xz linux-dev-2ef75e9bd2c998f1c6f6f23a3744136105ddefd5.zip | |
tracing: Don't use out-of-sync va_list in event printing
If trace_seq becomes full, trace_seq_vprintf() no longer consumes
arguments from va_list, making va_list out of sync with format
processing by trace_check_vprintf().
This causes va_arg() in trace_check_vprintf() to return wrong
positional argument, which results into a WARN_ON_ONCE() hit.
ftrace_stress_test from LTP triggers this situation.
Fix it by explicitly avoiding further use if va_list at the point
when it's consistency can no longer be guaranteed.
Link: https://lkml.kernel.org/r/20211118145516.13219-1-nikita.yushchenko@virtuozzo.com
Signed-off-by: Nikita Yushchenko <nikita.yushchenko@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e3c80cfd4eec..88de94da596b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3812,6 +3812,18 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, iter->fmt[i] = '\0'; trace_seq_vprintf(&iter->seq, iter->fmt, ap); + /* + * If iter->seq is full, the above call no longer guarantees + * that ap is in sync with fmt processing, and further calls + * to va_arg() can return wrong positional arguments. + * + * Ensure that ap is no longer used in this case. + */ + if (iter->seq.full) { + p = ""; + break; + } + if (star) len = va_arg(ap, int); |