From 1cab6bce42e62bba2ff2c2370d139618c1828b42 Mon Sep 17 00:00:00 2001 From: Kalesh Singh Date: Fri, 12 Nov 2021 11:13:24 -0800 Subject: tracing/histogram: Fix check for missing operands in an expression If a binary operation is detected while parsing an expression string, the operand strings are deduced by splitting the experssion string at the position of the detected binary operator. Both operand strings are sub-strings (can be empty string) of the expression string but will never be NULL. Currently a NULL check is used for missing operands, fix this by checking for empty strings instead. Link: https://lkml.kernel.org/r/20211112191324.1302505-1-kaleshsingh@google.com Signed-off-by: Kalesh Singh Fixes: 9710b2f341a0 ("tracing: Fix operator precedence for hist triggers expression") Reported-by: Dan Carpenter Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_events_hist.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 6a9fa34e2785..1475d7347fe0 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -2581,7 +2581,8 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data, operand1_str = str; str = sep+1; - if (!operand1_str || !str) + /* Binary operator requires both operands */ + if (*operand1_str == '\0' || *str == '\0') goto free; operand_flags = 0; -- cgit v1.2.3