The problem report was for a crash that happened when smbfs was

trying to do a mount. Given the backtrace,
it appears that the crash occurred when smb_vc_create() failed and then
called smb_vc_put() with vcp->vc_iod == NULL. smb_vc_put() subsequently
called smb_vc_disconnect() with vcp->vc_iod == NULL, causing the crash.
This patch adds a check for vcp->vc_iod != NULL in smb_vc_disconnect() to
avoid the crash. It also fixes the case in smb_vc_create() where
kproc_create() fails so that it destroys the mutexes and sets
vcp->vc_iod == NULL before free()'ing the iod structure.
The person who reported the PR tested the patch, but was not able
to reproduce the crash with or without the patch.

PR:		201912
Reviewed by:	jhb
MFC after:	2 weeks

2 files changed, 6 insertions, 1 deletions

diff --git a/sys/netsmb/smb_conn.c b/sys/netsmb/smb_conn.c
index d58bc72..adc171c 100644
--- a/sys/netsmb/smb_conn.c
+++ b/sys/netsmb/smb_conn.c
@@ -683,7 +683,9 @@ int
 smb_vc_disconnect(struct smb_vc *vcp)
 {
 
-	smb_iod_request(vcp->vc_iod, SMBIOD_EV_DISCONNECT | SMBIOD_EV_SYNC, NULL);
+	if (vcp->vc_iod != NULL)
+		smb_iod_request(vcp->vc_iod, SMBIOD_EV_DISCONNECT |
+		    SMBIOD_EV_SYNC, NULL);
 	return 0;
 }
 
diff --git a/sys/netsmb/smb_iod.c b/sys/netsmb/smb_iod.c
index ae5c6f7..412f816 100644
--- a/sys/netsmb/smb_iod.c
+++ b/sys/netsmb/smb_iod.c
@@ -690,6 +690,9 @@ smb_iod_create(struct smb_vc *vcp)
 	    RFNOWAIT, 0, "smbiod%d", iod->iod_id);
 	if (error) {
 		SMBERROR("can't start smbiod: %d", error);
+		vcp->vc_iod = NULL;
+		smb_sl_destroy(&iod->iod_rqlock);
+		smb_sl_destroy(&iod->iod_evlock);
 		free(iod, M_SMBIOD);
 		return error;
 	}