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Subject[PATCH 3.18 07/56] scsi: libiscsi: fix possible NULL pointer dereference in case of TMF
Date
3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Varun Prakash <varun@chelsio.com>

[ Upstream commit a17037e7d59075053b522048742a08ac9500bde8 ]

In iscsi_check_tmf_restrictions() task->hdr is dereferenced to print the
opcode, it is possible that task->hdr is NULL.

There are two cases based on opcode argument:

1. ISCSI_OP_SCSI_CMD - In this case alloc_pdu() is called
after iscsi_check_tmf_restrictions()

iscsi_prep_scsi_cmd_pdu() -> iscsi_check_tmf_restrictions() -> alloc_pdu().

Transport drivers allocate memory for iSCSI hdr in alloc_pdu() and assign
it to task->hdr. In case of TMF task->hdr will be NULL resulting in NULL
pointer dereference.

2. ISCSI_OP_SCSI_DATA_OUT - In this case transport driver can free the
memory for iSCSI hdr after transmitting the pdu so task->hdr can be NULL or
invalid.

This patch fixes this issue by removing task->hdr->opcode from the printk
statement.

Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/libiscsi.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -283,11 +283,11 @@ static int iscsi_check_tmf_restrictions(
*/
if (opcode != ISCSI_OP_SCSI_DATA_OUT) {
iscsi_conn_printk(KERN_INFO, conn,
- "task [op %x/%x itt "
+ "task [op %x itt "
"0x%x/0x%x] "
"rejected.\n",
- task->hdr->opcode, opcode,
- task->itt, task->hdr_itt);
+ opcode, task->itt,
+ task->hdr_itt);
return -EACCES;
}
/*
@@ -296,10 +296,10 @@ static int iscsi_check_tmf_restrictions(
*/
if (conn->session->fast_abort) {
iscsi_conn_printk(KERN_INFO, conn,
- "task [op %x/%x itt "
+ "task [op %x itt "
"0x%x/0x%x] fast abort.\n",
- task->hdr->opcode, opcode,
- task->itt, task->hdr_itt);
+ opcode, task->itt,
+ task->hdr_itt);
return -EACCES;
}
break;

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