linux-kernel - [PATCH] Add NULL check for SCp in process_script

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Message-Id: <20240221120414.29192-1-adiupina@astralinux.ru>
Date: Wed, 21 Feb 2024 15:04:14 +0300
From: Alexandra Diupina <adiupina@...ralinux.ru>
To: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>
Cc: Alexandra Diupina <adiupina@...ralinux.ru>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: [PATCH] Add NULL check for SCp in process_script_interrupt()

SCp is 3rd argument of process_script_interrupt()
(calls in drivers/scsi/53c700.c:1346 where SCp != NULL and
drivers/scsi/53c700.c:1672 where this condition is not guaranteed).
Before call process_script_interrupt() in drivers/scsi/53c700.c:1672
there is SCp = hostdata->cmd, wherein (type casts omitted)
hostdata = host->hostdata[0], host = dev_id,
dev_id - 2nd argument of NCR_700_intr().
NCR_700_intr() is used when calling request_irq() -> request_threaded_irq()
as the 2nd argument.
Last argument of call request_irq(..., NCR_700_intr, ... host) is host.
host = NCR_700_detect(), host->hostdata[0] = hostdata, hostdata->cmd = NULL.
So, there is possible NULL pointer dereference,
so add NULL check for SCp in process_script_interrupt() to avoid it.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Alexandra Diupina <adiupina@...ralinux.ru>
---
 drivers/scsi/53c700.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/53c700.c b/drivers/scsi/53c700.c
index 857be0f3ae5b..54bcc5727fbb 100644
--- a/drivers/scsi/53c700.c
+++ b/drivers/scsi/53c700.c
@@ -1067,7 +1067,7 @@ process_script_interrupt(__u32 dsps, __u32 dsp, struct scsi_cmnd *SCp,
 			//}
 			NCR_700_scsi_done(hostdata, SCp, hostdata->status[0]);
 		}
-	} else if((dsps & 0xfffff0f0) == A_UNEXPECTED_PHASE) {
+	} else if ((dsps & 0xfffff0f0) == A_UNEXPECTED_PHASE && SCp) {
 		__u8 i = (dsps & 0xf00) >> 8;

 		scmd_printk(KERN_ERR, SCp, "UNEXPECTED PHASE %s (%s)\n",
-- 
2.30.2