[PATCH 4.19 02/11] tracing: Reject string operand in the histogram expression

Greg Kroah-Hartman
2021-08-13T15:15:46Z

From: Masami Hiramatsu <mhiramat@kernel.org>

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>
---
kernel/trace/trace_events_hist.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2790,6 +2790,12 @@ static struct hist_field *parse_unary(st
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(str
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(str
operand2 = NULL;
goto free;
}
+ if (operand2->flags & HIST_FIELD_FL_STRING) {
+ ret = -EINVAL;
+ goto free;
+ }

ret = check_expr_operands(operand1, operand2);
if (ret)