On 2023-12-12 08:44, Steven Rostedt wrote:
From: "Steven Rostedt (Google)" <rost...@goodmis.org>
If for some reason the trace_marker write does not have a nul byte for the
string, it will overflow the print:
Does this result in leaking kernel memory to userspace ? If so, it
should state "Fixes..." and CC stable.
Thanks,
Mathieu
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);
Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
kernel/trace/trace_output.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index d8b302d01083..e11fb8996286 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1587,11 +1587,12 @@ 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);
}
@@ -1600,10 +1601,11 @@ 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);
}
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
