tracing: Reject string operand in the histogram expression

commit a9d10ca4986571bffc19778742d508cc8dd13e02 upstream.

Since the string type can not be the target of the addition / subtraction
operation, it must be rejected. Without this fix, the string type silently
converted to digits.

Link: https://lkml.kernel.org/r/162742654278.290973.1523000673366456634.stgit@devnote2
Cc: stable@vger.kernel.org
Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 6d2a69652c391776dc673e76d0c11d2051c7209b..bbde8d3d6c8ae9534bda1088176c3417525612ac 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2790,6 +2790,12 @@ static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
                ret = PTR_ERR(operand1);
                goto free;
        }
+       if (operand1->flags & HIST_FIELD_FL_STRING) {
+               /* String type can not be the operand of unary operator. */
+               destroy_hist_field(operand1, 0);
+               ret = -EINVAL;
+               goto free;
+       }
 
        expr->flags |= operand1->flags &
                (HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
@@ -2890,6 +2896,10 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
                operand1 = NULL;
                goto free;
        }
+       if (operand1->flags & HIST_FIELD_FL_STRING) {
+               ret = -EINVAL;
+               goto free;
+       }
 
        /* rest of string could be another expression e.g. b+c in a+b+c */
        operand_flags = 0;
@@ -2899,6 +2909,10 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
                operand2 = NULL;
                goto free;
        }
+       if (operand2->flags & HIST_FIELD_FL_STRING) {
+               ret = -EINVAL;
+               goto free;
+       }
 
        ret = check_expr_operands(operand1, operand2);
        if (ret)