Fixes a use-after-free reported by KASAN when later
iscsi_target_login_sess_out gets called and it tries to access
conn->sess->se_sess:
Disabling lock debugging due to kernel taint
iSCSI Login timeout on Network Portal [::]:3260
iSCSI Login negotiation failed.
==================================================================
BUG: KASAN: use-after-free in iscsi_target_login_sess_out.cold.12+0x58/0xff [iscsi_target_mod]
Read of size 8 at addr ffff880109d070c8 by task iscsi_np/980
CPU: 1 PID: 980 Comm: iscsi_np Tainted: G O 4.17.8kasan.sess.connops+ #4
Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 05/19/2014
Call Trace:
dump_stack+0x71/0xac
print_address_description+0x65/0x22e
? iscsi_target_login_sess_out.cold.12+0x58/0xff [iscsi_target_mod]
kasan_report.cold.6+0x241/0x2fd
iscsi_target_login_sess_out.cold.12+0x58/0xff [iscsi_target_mod]
iscsi_target_login_thread+0x1086/0x1710 [iscsi_target_mod]
? __sched_text_start+0x8/0x8
? iscsi_target_login_sess_out+0x250/0x250 [iscsi_target_mod]
? __kthread_parkme+0xcc/0x100
? parse_args.cold.14+0xd3/0xd3
? iscsi_target_login_sess_out+0x250/0x250 [iscsi_target_mod]
kthread+0x1a0/0x1c0
? kthread_bind+0x30/0x30
ret_from_fork+0x35/0x40
Allocated by task 980:
kasan_kmalloc+0xbf/0xe0
kmem_cache_alloc_trace+0x112/0x210
iscsi_target_login_thread+0x816/0x1710 [iscsi_target_mod]
kthread+0x1a0/0x1c0
ret_from_fork+0x35/0x40
Freed by task 980:
__kasan_slab_free+0x125/0x170
kfree+0x90/0x1d0
iscsi_target_login_thread+0x1577/0x1710 [iscsi_target_mod]
kthread+0x1a0/0x1c0
ret_from_fork+0x35/0x40
The buggy address belongs to the object at ffff880109d06f00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 456 bytes inside of
512-byte region [ffff880109d06f00, ffff880109d07100)
The buggy address belongs to the page:
page:ffffea0004274180 count:1 mapcount:0 mapping:0000000000000000 index:0x0 compound_mapcount: 0
flags: 0x17fffc000008100(slab|head)
raw: 017fffc000008100 0000000000000000 0000000000000000 00000001000c000c
raw: dead000000000100 dead000000000200 ffff88011b002e00 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff880109d06f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff880109d07000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff880109d07080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff880109d07100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff880109d07180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Also, let idr_alloc return value through instead of replacing it with -ENOMEM,
as it is already a negative value and caller checks sign, not exact value.
Signed-off-by: Vincent Pelletier <plr.vincent@xxxxxxxxx>
---
drivers/target/iscsi/iscsi_target_login.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index df81b2f7cad9..7337ff80394e 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -296,10 +296,8 @@ static int iscsi_login_zero_tsih_s1(
}
ret = iscsi_login_set_conn_values(sess, conn, pdu->cid);
- if (unlikely(ret)) {
- kfree(sess);
- return ret;
- }
+ if (unlikely(ret))
+ goto free_sess;
sess->init_task_tag = pdu->itt;
memcpy(&sess->isid, pdu->isid, 6);
sess->exp_cmd_sn = be32_to_cpu(pdu->cmdsn);
@@ -349,6 +347,7 @@ static int iscsi_login_zero_tsih_s1(
ISCSI_LOGIN_STATUS_NO_RESOURCES);
pr_err("Unable to allocate memory for"
" struct iscsi_sess_ops.\n");
+ ret = -ENOMEM;
goto remove_idr;
}
@@ -356,6 +355,7 @@ static int iscsi_login_zero_tsih_s1(
if (IS_ERR(sess->se_sess)) {
iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
ISCSI_LOGIN_STATUS_NO_RESOURCES);
+ ret = -ENOMEM;
goto free_ops;
}
@@ -370,7 +370,7 @@ static int iscsi_login_zero_tsih_s1(
free_sess:
kfree(sess);
conn->sess = NULL;
- return -ENOMEM;
+ return ret;
}
static int iscsi_login_zero_tsih_s2(
--
2.18.0
