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Commit d1ad09db authored by Heiko Carstens's avatar Heiko Carstens Committed by James Bottomley
Browse files

[SCSI] zfcp: fix use after free bug. 



zfcp_erp_strategy_check_fsfreq() checks if it is safe to access the
fsf_req associated with the erp_action that gets passed. To test if
it is safe it accesses the fsf_req in order to get its index into
the hash list. This is broken since the fsf_req might be freed already
and the read index has no meaning. It could lead to memory corruption.
Fix this by introducing a new zfcp_reqlist_find_safe() method which
just checks if addresses are equal. This is slower, but only gets
called in case of error recovery.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarChristof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: default avatarMartin Peschke <mp3@de.ibm.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent bfd90dce

drivers/s390/scsi/zfcp_def.h

+14 −0
Original line number Diff line number Diff line
@@ -1123,6 +1123,20 @@ zfcp_reqlist_find(struct zfcp_adapter *adapter, unsigned long req_id) 
	return NULL;

}



static inline struct zfcp_fsf_req *

zfcp_reqlist_find_safe(struct zfcp_adapter *adapter, struct zfcp_fsf_req *req)

{

	struct zfcp_fsf_req *request;

	unsigned int idx;



	for (idx = 0; idx < REQUEST_LIST_SIZE; idx++) {

		list_for_each_entry(request, &adapter->req_list[idx], list)

			if (request == req)

				return request;

	}

	return NULL;

}



/*

 *  functions needed for reference/usage counting

 */

drivers/s390/scsi/zfcp_erp.c

+2 −1
Original line number Diff line number Diff line
@@ -846,7 +846,8 @@ zfcp_erp_strategy_check_fsfreq(struct zfcp_erp_action *erp_action) 
	if (erp_action->fsf_req) {

		/* take lock to ensure that request is not deleted meanwhile */

		spin_lock(&adapter->req_list_lock);

		if (zfcp_reqlist_find(adapter, erp_action->fsf_req->req_id)) {

		if (zfcp_reqlist_find_safe(adapter, erp_action->fsf_req) &&

		    erp_action->fsf_req->erp_action == erp_action) {

			/* fsf_req still exists */

			debug_text_event(adapter->erp_dbf, 3, "a_ca_req");

			debug_event(adapter->erp_dbf, 3, &erp_action->fsf_req,