tracing/filters: Fix error-handling of cpulist parsing buffer

parse_pred() allocates a string buffer to parse the user-provided cpulist,
but doesn't check the allocation result nor does it free the buffer once it
is no longer needed.

Add an allocation check, and free the buffer as soon as it is no longer
needed.

Link: https://lkml.kernel.org/r/20230901151039.125186-2-vschneid@redhat.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 3a529214a21b7cf79c8133e9defffe6bfec330e6..c06e1d596f4b9474de8b6ab09e9df14f6c482257 100644 (file)
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1744,17 +1744,23 @@ static int parse_pred(const char *str, void *data,
 
                /* Copy the cpulist between { and } */
                tmp = kmalloc((i - maskstart) + 1, GFP_KERNEL);
-               strscpy(tmp, str + maskstart, (i - maskstart) + 1);
+               if (!tmp)
+                       goto err_mem;
 
+               strscpy(tmp, str + maskstart, (i - maskstart) + 1);
                pred->mask = kzalloc(cpumask_size(), GFP_KERNEL);
-               if (!pred->mask)
+               if (!pred->mask) {
+                       kfree(tmp);
                        goto err_mem;
+               }
 
                /* Now parse it */
                if (cpulist_parse(tmp, pred->mask)) {
+                       kfree(tmp);
                        parse_error(pe, FILT_ERR_INVALID_CPULIST, pos + i);
                        goto err_free;
                }
+               kfree(tmp);
 
                /* Move along */
                i++;