Patch "tracing: Fix parse_synth_field() error handling" has been added to the 5.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    tracing: Fix parse_synth_field() error handling

to the 5.8-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-fix-parse_synth_field-error-handling.patch
and it can be found in the queue-5.8 subdirectory.

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



commit a13dc65d832db9a1c78952b3bcbeea0a9ee146fe
Author: Tom Zanussi <zanussi@xxxxxxxxxx>
Date:   Sun Oct 4 17:14:04 2020 -0500

    tracing: Fix parse_synth_field() error handling
    
    [ Upstream commit 8fbeb52a598c7ab5aa603d6bb083b8a8d16d607a ]
    
    synth_field_size() returns either a positive size or an error (zero or
    a negative value). However, the existing code assumes the only error
    value is 0. It doesn't handle negative error codes, as it assigns
    directly to field->size (a size_t; unsigned), thereby interpreting the
    error code as a valid size instead.
    
    Do the test before assignment to field->size.
    
    [ axelrasmussen@xxxxxxxxxx: changelog addition, first paragraph above ]
    
    Link: https://lkml.kernel.org/r/9b6946d9776b2eeb43227678158196de1c3c6e1d.1601848695.git.zanussi@xxxxxxxxxx
    
    Fixes: 4b147936fa50 (tracing: Add support for 'synthetic' events)
    Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Tested-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
    Signed-off-by: Tom Zanussi <zanussi@xxxxxxxxxx>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index c6cca0d1d5840..46a96686e93c6 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -465,6 +465,7 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
 	struct synth_field *field;
 	const char *prefix = NULL, *field_type = argv[0], *field_name, *array;
 	int len, ret = 0;
+	ssize_t size;
 
 	if (field_type[0] == ';')
 		field_type++;
@@ -520,11 +521,12 @@ static struct synth_field *parse_synth_field(int argc, const char **argv,
 			field->type[len - 1] = '\0';
 	}
 
-	field->size = synth_field_size(field->type);
-	if (!field->size) {
+	size = synth_field_size(field->type);
+	if (size <= 0) {
 		ret = -EINVAL;
 		goto free;
 	}
+	field->size = size;
 
 	if (synth_field_is_string(field->type))
 		field->is_string = true;