libceph: don't access invalid memory in keepalive2 path

This

    struct ceph_timespec ceph_ts;
    ...
    con_out_kvec_add(con, sizeof(ceph_ts), &ceph_ts);

wraps ceph_ts into a kvec and adds it to con->out_kvec array, yet
ceph_ts becomes invalid on return from prepare_write_keepalive().  As
a result, we send out bogus keepalive2 stamps.  Fix this by encoding
into a ceph_timespec member, similar to how acks are read and written.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>

2 files changed, 8 insertions, 5 deletions

diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index 7e1252e97a30..b2371d9b51fa 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -238,6 +238,8 @@ struct ceph_connection {
         bool out_kvec_is_msg; /* kvec refers to out_msg */
         int out_more;        /* there is more data after the kvecs */
         __le64 out_temp_ack; /* for writing an ack */
+        struct ceph_timespec out_temp_keepalive2; /* for writing keepalive2
+                                                     stamp */
 
         /* message in temps */
         struct ceph_msg_header in_hdr;
@@ -248,7 +250,7 @@ struct ceph_connection {
         int in_base_pos;     /* bytes read */
         __le64 in_temp_ack;  /* for reading an ack */
 
-        struct timespec last_keepalive_ack;
+        struct timespec last_keepalive_ack; /* keepalive2 ack stamp */
 
         struct delayed_work work;           /* send|recv work */
         unsigned long       delay;          /* current delay interval */
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 525f454f7531..b9b0e3b5da49 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1353,11 +1353,12 @@ static void prepare_write_keepalive(struct ceph_connection *con)
         dout("prepare_write_keepalive %p\n", con);
         con_out_kvec_reset(con);
         if (con->peer_features & CEPH_FEATURE_MSGR_KEEPALIVE2) {
-                struct timespec ts = CURRENT_TIME;
-                struct ceph_timespec ceph_ts;
-                ceph_encode_timespec(&ceph_ts, &ts);
+                struct timespec now = CURRENT_TIME;
+
                 con_out_kvec_add(con, sizeof(tag_keepalive2), &tag_keepalive2);
-                con_out_kvec_add(con, sizeof(ceph_ts), &ceph_ts);
+                ceph_encode_timespec(&con->out_temp_keepalive2, &now);
+                con_out_kvec_add(con, sizeof(con->out_temp_keepalive2),
+                                 &con->out_temp_keepalive2);
         } else {
                 con_out_kvec_add(con, sizeof(tag_keepalive), &tag_keepalive);
         }