[SCSI] zfcp: fix use after free bug. (d1ad09db) · Commits · 戴 / test

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:

Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by:

Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by:

Christof Schmitt <christof.schmitt@de.ibm.com> Signed-off-by:

Martin Peschke <mp3@de.ibm.com> Signed-off-by:

James Bottomley <James.Bottomley@HansenPartnership.com>

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,

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