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[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: 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>
This commit is contained in:
Heiko Carstens 2007-12-20 12:30:22 +01:00 committed by James Bottomley
parent bfd90dce24
commit d1ad09db2f
2 changed files with 16 additions and 1 deletions
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14
drivers/s390/scsi/zfcp_def.h
View File

@ -1123,6 +1123,20 @@ zfcp_reqlist_find(struct zfcp_adapter *adapter, unsigned long req_id)
return NULL; 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 * functions needed for reference/usage counting
*/ */

3
drivers/s390/scsi/zfcp_erp.c
View File

@ -846,7 +846,8 @@ zfcp_erp_strategy_check_fsfreq(struct zfcp_erp_action *erp_action)
if (erp_action->fsf_req) { if (erp_action->fsf_req) {
/* take lock to ensure that request is not deleted meanwhile */ /* take lock to ensure that request is not deleted meanwhile */
spin_lock(&adapter->req_list_lock); 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 */ /* fsf_req still exists */
debug_text_event(adapter->erp_dbf, 3, "a_ca_req"); debug_text_event(adapter->erp_dbf, 3, "a_ca_req");
debug_event(adapter->erp_dbf, 3, &erp_action->fsf_req, debug_event(adapter->erp_dbf, 3, &erp_action->fsf_req,