From: "Steven Rostedt (VMware)" rostedt@goodmis.org
The syzkaller detected a out-of-bounds issue with the events filter code, specifically here:
prog[N].pred = NULL; /* #13 */ prog[N].target = 1; /* TRUE */ prog[N+1].pred = NULL; prog[N+1].target = 0; /* FALSE */ -> prog[N-1].target = N; prog[N-1].when_to_branch = false;
As that's the first reference to a "N-1" index, it appears that the code got here with N = 0, which means the filter parser found no filter to parse (which shouldn't ever happen, but apparently it did).
Add a new error to the parsing code that will check to make sure that N is not zero before going into this part of the code. If N = 0, then -EINVAL is returned, and a error message is added to the filter.
Cc: stable@vger.kernel.org Fixes: 80765597bc587 ("tracing: Rewrite filter logic to be simpler and faster") Reported-by: air icy icytxw@gmail.com bugzilla url: https://bugzilla.kernel.org/show_bug.cgi?id=200019 Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org --- kernel/trace/trace_events_filter.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index e1c818dbc0d7..0dceb77d1d42 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -78,7 +78,8 @@ static const char * ops[] = { OPS }; C(TOO_MANY_PREDS, "Too many terms in predicate expression"), \ C(INVALID_FILTER, "Meaningless filter expression"), \ C(IP_FIELD_ONLY, "Only 'ip' field is supported for function trace"), \ - C(INVALID_VALUE, "Invalid value (did you forget quotes)?"), + C(INVALID_VALUE, "Invalid value (did you forget quotes)?"), \ + C(NO_FILTER, "No filter found"),
#undef C #define C(a, b) FILT_ERR_##a @@ -550,6 +551,13 @@ predicate_parse(const char *str, int nr_parens, int nr_preds, goto out_free; }
+ if (!N) { + /* No program? */ + ret = -EINVAL; + parse_error(pe, FILT_ERR_NO_FILTER, ptr - str); + goto out_free; + } + prog[N].pred = NULL; /* #13 */ prog[N].target = 1; /* TRUE */ prog[N+1].pred = NULL;