scsi: qla2xxx: Fix use after free in bsg

On bsg command completion, bsg_job_done() was called while qla driver
continued to access the bsg_job buffer. bsg_job_done() would free up
resources that ended up being reused by other task while the driver
continued to access the buffers. As a result, driver was reading garbage
data.

localhost kernel: BUG: KASAN: use-after-free in sg_next+0x64/0x80
localhost kernel: Read of size 8 at addr ffff8883228a3330 by task swapper/26/0
localhost kernel:
localhost kernel: CPU: 26 PID: 0 Comm: swapper/26 Kdump:
loaded Tainted: G          OE    --------- -  - 4.18.0-193.el8.x86_64+debug #1
localhost kernel: Hardware name: HP ProLiant DL360
Gen9/ProLiant DL360 Gen9, BIOS P89 08/12/2016
localhost kernel: Call Trace:
localhost kernel: <IRQ>
localhost kernel: dump_stack+0x9a/0xf0
localhost kernel: print_address_description.cold.3+0x9/0x23b
localhost kernel: kasan_report.cold.4+0x65/0x95
localhost kernel: debug_dma_unmap_sg.part.12+0x10d/0x2d0
localhost kernel: qla2x00_bsg_sp_free+0xaf6/0x1010 [qla2xxx]

Link: https://lore.kernel.org/r/20210329085229.4367-6-njavali@marvell.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Quinn Tran <qutran@marvell.com>
Signed-off-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Quinn Tran

drivers/scsi/qla2xxx/qla_bsg.c

@@ -25,10 +25,11 @@ void qla2x00_bsg_job_done(srb_t *sp, int res)
 	struct bsg_job *bsg_job = sp->u.bsg_job;
 	struct fc_bsg_reply *bsg_reply = bsg_job->reply;
 
+	sp->free(sp);
+
 	bsg_reply->result = res;
 	bsg_job_done(bsg_job, bsg_reply->result,
 		       bsg_reply->reply_payload_rcv_len);
-	sp->free(sp);
 }
 
 void qla2x00_bsg_sp_free(srb_t *sp)