Patch "tracing: Add size check when printing trace_marker output" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tracing: Add size check when printing trace_marker output

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tracing-add-size-check-when-printing-trace_marker-ou.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 3236c58263eb8574ae91c69ae30aaac03b4109d0
Author: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Date:   Tue Dec 12 08:44:44 2023 -0500

    tracing: Add size check when printing trace_marker output
    
    [ Upstream commit 60be76eeabb3d83858cc6577fc65c7d0f36ffd42 ]
    
    If for some reason the trace_marker write does not have a nul byte for the
    string, it will overflow the print:
    
      trace_seq_printf(s, ": %s", field->buf);
    
    The field->buf could be missing the nul byte. To prevent overflow, add the
    max size that the buf can be by using the event size and the field
    location.
    
      int max = iter->ent_size - offsetof(struct print_entry, buf);
    
      trace_seq_printf(s, ": %*.s", max, field->buf);
    
    Link: https://lore.kernel.org/linux-trace-kernel/20231212084444.4619b8ce@xxxxxxxxxxxxxxxxxx
    
    Cc: Mark Rutland <mark.rutland@xxxxxxx>
    Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
    Reviewed-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
    Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index b194dd1c8420..9ffe54ff3edb 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1291,11 +1291,12 @@ static enum print_line_t trace_print_print(struct trace_iterator *iter,
 {
 	struct print_entry *field;
 	struct trace_seq *s = &iter->seq;
+	int max = iter->ent_size - offsetof(struct print_entry, buf);
 
 	trace_assign_type(field, iter->ent);
 
 	seq_print_ip_sym(s, field->ip, flags);
-	trace_seq_printf(s, ": %s", field->buf);
+	trace_seq_printf(s, ": %.*s", max, field->buf);
 
 	return trace_handle_return(s);
 }
@@ -1304,10 +1305,11 @@ static enum print_line_t trace_print_raw(struct trace_iterator *iter, int flags,
 					 struct trace_event *event)
 {
 	struct print_entry *field;
+	int max = iter->ent_size - offsetof(struct print_entry, buf);
 
 	trace_assign_type(field, iter->ent);
 
-	trace_seq_printf(&iter->seq, "# %lx %s", field->ip, field->buf);
+	trace_seq_printf(&iter->seq, "# %lx %.*s", field->ip, max, field->buf);
 
 	return trace_handle_return(&iter->seq);
 }