4.16-stable review patch. If anyone has any objections, please let me know.
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From: Steven Rostedt (VMware) rostedt@goodmis.org
commit dc432c3d7f9bceb3de6f5b44fb9c657c9810ed6d upstream.
The regex match function regex_match_front() in the tracing filter logic, was fixed to test just the pattern length from testing the entire test string. That is, it went from strncmp(str, r->pattern, len) to strcmp(str, r->pattern, r->len).
The issue is that str is not guaranteed to be nul terminated, and if r->len is greater than the length of str, it can access more memory than is allocated.
The solution is to add a simple test if (len < r->len) return 0.
Cc: stable@vger.kernel.org Fixes: 285caad415f45 ("tracing/filters: Fix MATCH_FRONT_ONLY filter matching") Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/trace/trace_events_filter.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -338,6 +338,9 @@ static int regex_match_full(char *str, s
static int regex_match_front(char *str, struct regex *r, int len) { + if (len < r->len) + return 0; + if (strncmp(str, r->pattern, r->len) == 0) return 1; return 0;