From: Steffen Maier Date: Wed, 8 Feb 2017 14:34:22 +0000 (+0100) Subject: scsi: zfcp: fix use-after-free by not tracing WKA port open/close on failed send X-Git-Tag: v3.2.87~61 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=41cf7ba330bdd5f888268d26513ee707a1cb8e23;p=pandora-kernel.git scsi: zfcp: fix use-after-free by not tracing WKA port open/close on failed send commit 2dfa6688aafdc3f74efeb1cf05fb871465d67f79 upstream. Dan Carpenter kindly reported: The patch d27a7cb91960: "zfcp: trace on request for open and close of WKA port" from Aug 10, 2016, leads to the following static checker warning: drivers/s390/scsi/zfcp_fsf.c:1615 zfcp_fsf_open_wka_port() warn: 'req' was already freed. drivers/s390/scsi/zfcp_fsf.c 1609 zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT); 1610 retval = zfcp_fsf_req_send(req); 1611 if (retval) 1612 zfcp_fsf_req_free(req); ^^^ Freed. 1613 out: 1614 spin_unlock_irq(&qdio->req_q_lock); 1615 if (req && !IS_ERR(req)) 1616 zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id); ^^^^^^^^^^^ Use after free. 1617 return retval; 1618 } Same thing for zfcp_fsf_close_wka_port() as well. Rather than relying on req being NULL (or ERR_PTR) for all cases where we don't want to trace or should not trace, simply check retval which is unconditionally initialized with -EIO != 0 and it can only become 0 on successful retval = zfcp_fsf_req_send(req). With that we can also remove the then again unnecessary unconditional initialization of req which was introduced with that earlier commit. Reported-by: Dan Carpenter Suggested-by: Benjamin Block Signed-off-by: Steffen Maier Fixes: d27a7cb91960 ("zfcp: trace on request for open and close of WKA port") Reviewed-by: Benjamin Block Reviewed-by: Jens Remus Signed-off-by: Martin K. Petersen Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed