tracing: Reject string operand in the histogram expression

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>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 362db9b..949ef09 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -65,7 +65,8 @@
        C(INVALID_SORT_MODIFIER,"Invalid sort modifier"),               \
        C(EMPTY_SORT_FIELD,     "Empty sort field"),                    \
        C(TOO_MANY_SORT_FIELDS, "Too many sort fields (Max = 2)"),      \
-       C(INVALID_SORT_FIELD,   "Sort field must be a key or a val"),
+       C(INVALID_SORT_FIELD,   "Sort field must be a key or a val"),   \
+       C(INVALID_STR_OPERAND,  "String type can not be an operand in expression"),
 
 #undef C
 #define C(a, b)                HIST_ERR_##a
@@ -2156,6 +2157,13 @@ 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. */
+               hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(str));
+               destroy_hist_field(operand1, 0);
+               ret = -EINVAL;
+               goto free;
+       }
 
        expr->flags |= operand1->flags &
                (HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
@@ -2257,6 +2265,11 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
                operand1 = NULL;
                goto free;
        }
+       if (operand1->flags & HIST_FIELD_FL_STRING) {
+               hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(operand1_str));
+               ret = -EINVAL;
+               goto free;
+       }
 
        /* rest of string could be another expression e.g. b+c in a+b+c */
        operand_flags = 0;
@@ -2266,6 +2279,11 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
                operand2 = NULL;
                goto free;
        }
+       if (operand2->flags & HIST_FIELD_FL_STRING) {
+               hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(str));
+               ret = -EINVAL;
+               goto free;
+       }
 
        ret = check_expr_operands(file->tr, operand1, operand2);
        if (ret)