From: Beau Belgrave beaub@linux.microsoft.com

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.

Link: https://lkml.kernel.org/r/20230629235049.581-2-beaub@linux.microsoft.com

Cc: stable@vger.kernel.org Fixes: e6f89a149872 ("tracing/user_events: Ensure user provided strings are safely formatted") Signed-off-by: Beau Belgrave beaub@linux.microsoft.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- kernel/trace/trace_events_user.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index dbb14705d0d3..83c0536ff41c 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -1223,6 +1223,9 @@ 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, ";");