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tracing: Add size check when printing trace_marker output

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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@gandalf.local.home

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2023-12-12 08:44:44 -05:00
parent b049525855
commit 60be76eeab
1 changed files with 4 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

6
kernel/trace/trace_output.c
View file

@ -1587,11 +1587,12 @@ static enum print_line_t trace_print_print(struct trace_iterator *iter,
{ {
struct print_entry *field; struct print_entry *field;
struct trace_seq *s = &iter->seq; struct trace_seq *s = &iter->seq;
int max = iter->ent_size - offsetof(struct print_entry, buf);
trace_assign_type(field, iter->ent); trace_assign_type(field, iter->ent);
seq_print_ip_sym(s, field->ip, flags); 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); return trace_handle_return(s);
} }
@ -1600,10 +1601,11 @@ static enum print_line_t trace_print_raw(struct trace_iterator *iter, int flags,
struct trace_event *event) struct trace_event *event)
{ {
struct print_entry *field; struct print_entry *field;
int max = iter->ent_size - offsetof(struct print_entry, buf);
trace_assign_type(field, iter->ent); 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); return trace_handle_return(&iter->seq);
} }