[PATCH 3.12 78/82] target: Fix free-after-use regression in PR unregister

Greg Kroah-Hartman
2014-02-21T00:22:51Z

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit fc09149df6e20cfbb0bb86f10899607c321a31eb upstream.

This patch addresses a >= v3.11 free-after-use regression
in core_scsi3_emulate_pro_register() that was introduced
in the following commit:

commit bc118fe4c4a8cfa453491ba77c0a146a6d0e73e0
Author: Andy Grover <agrover@redhat.com>
Date: Thu May 16 10:41:04 2013 -0700

target: Further refactoring of core_scsi3_emulate_pro_register()

To avoid the free-after-use, save an type value before hand, and
only call core_scsi3_put_pr_reg() with a valid *pr_reg.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/target/target_core_pr.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -2009,7 +2009,7 @@ core_scsi3_emulate_pro_register(struct s
struct t10_reservation *pr_tmpl = &dev->t10_pr;
unsigned char isid_buf[PR_REG_ISID_LEN], *isid_ptr = NULL;
sense_reason_t ret = TCM_NO_SENSE;
- int pr_holder = 0;
+ int pr_holder = 0, type;

if (!se_sess || !se_lun) {
pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!\n");
@@ -2131,6 +2131,7 @@ core_scsi3_emulate_pro_register(struct s
ret = TCM_RESERVATION_CONFLICT;
goto out;
}
+ type = pr_reg->pr_res_type;

spin_lock(&pr_tmpl->registration_lock);
/*
@@ -2161,6 +2162,7 @@ core_scsi3_emulate_pro_register(struct s
* Release the calling I_T Nexus registration now..
*/
__core_scsi3_free_registration(cmd->se_dev, pr_reg, NULL, 1);
+ pr_reg = NULL;

/*
* From spc4r17, section 5.7.11.3 Unregistering
@@ -2174,8 +2176,8 @@ core_scsi3_emulate_pro_register(struct s
* RESERVATIONS RELEASED.
*/
if (pr_holder &&
- (pr_reg->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_REGONLY ||
- pr_reg->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_REGONLY)) {
+ (type == PR_TYPE_WRITE_EXCLUSIVE_REGONLY ||
+ type == PR_TYPE_EXCLUSIVE_ACCESS_REGONLY)) {
list_for_each_entry(pr_reg_p,
&pr_tmpl->registration_list,
pr_reg_list) {
@@ -2194,7 +2196,8 @@ core_scsi3_emulate_pro_register(struct s
ret = core_scsi3_update_and_write_aptpl(dev, aptpl);

out:
- core_scsi3_put_pr_reg(pr_reg);
+ if (pr_reg)
+ core_scsi3_put_pr_reg(pr_reg);
return ret;
}