[PATCH 5.16 117/227] mctp: fix use after free

Greg Kroah-Hartman
2022-02-21T10:03:02Z

From: Tom Rix <trix@redhat.com>

commit 7e5b6a5c8c44310784c88c1c198dde79f6402f7b upstream.

Clang static analysis reports this problem
route.c:425:4: warning: Use of memory after it is freed
trace_mctp_key_acquire(key);
^~~~~~~~~~~~~~~~~~~~~~~~~~~
When mctp_key_add() fails, key is freed but then is later
used in trace_mctp_key_acquire(). Add an else statement
to use the key only when mctp_key_add() is successful.

Fixes: 4f9e1ba6de45 ("mctp: Add tracepoints for tag/key handling")
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/mctp/route.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -414,13 +414,14 @@ static int mctp_route_input(struct mctp_
* this function.
*/
rc = mctp_key_add(key, msk);
- if (rc)
+ if (rc) {
kfree(key);
+ } else {
+ trace_mctp_key_acquire(key);

- trace_mctp_key_acquire(key);
-
- /* we don't need to release key->lock on exit */
- mctp_key_unref(key);
+ /* we don't need to release key->lock on exit */
+ mctp_key_unref(key);
+ }
key = NULL;

} else {