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[1/2] tracing/user_events: Fix struct arg size match check

Message ID 20230629235049.581-2-beaub@linux.microsoft.com
State New
Headers
Series tracing/user_events: Fix struct arg size match check |

Commit Message

Beau Belgrave June 29, 2023, 11:50 p.m. UTC 
  When users register an event the name of the event and it's argument are
checked to ensure they match if the event already exists. Normally all
arguments are in the form of "type name", except for when the type
starts with "struct ". In those cases, the size of the struct is passed
in addition to the name, IE: "struct my_struct a 20" for an argument
that is of type "struct my_struct" with a field name of "a" and has the
size of 20 bytes.

The current code does not honor the above case properly when comparing
a match. This causes the event register to fail even when the same
string was used for events that contain a struct argument within them.
The example above "struct my_struct a 20" generates a match string of
"struct my_struct a" omitting the size field.

Add the struct size of the existing field when generating a comparison
string for a struct field to ensure proper match checking.

Fixes: e6f89a149872 ("tracing/user_events: Ensure user provided strings are safely formatted")

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
---
 kernel/trace/trace_events_user.c | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index 8df0550415e7..5c787fe48d53 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -1317,6 +1317,9 @@  static int user_field_set_string(struct ftrace_event_field *field,
 	pos += snprintf(buf + pos, LEN_OR_ZERO, " ");
 	pos += snprintf(buf + pos, LEN_OR_ZERO, "%s", field->name);
 
+	if (str_has_prefix(field->type, "struct "))
+		pos += snprintf(buf + pos, LEN_OR_ZERO, " %d", field->size);
+
 	if (colon)
 		pos += snprintf(buf + pos, LEN_OR_ZERO, ";");