linux-kernel - [PATCH] scsi: fix uninitialized pointers with free attr

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Message-Id: <20251105-aheev-uninitialized-free-attr-scsi-v1-1-d28435a0a7ea@gmail.com>
Date: Wed, 05 Nov 2025 19:44:43 +0530
From: Ally Heev <allyheev@...il.com>
To: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>, 
 "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Dan Carpenter <dan.carpenter@...aro.org>, Ally Heev <allyheev@...il.com>
Subject: [PATCH] scsi: fix uninitialized pointers with free attr

Uninitialized pointers with `__free` attribute can cause undefined
behaviour as the memory assigned(randomly) to the pointer is freed
automatically when the pointer goes out of scope

scsi doesn't have any bugs related to this as of now, but
it is better to initialize and assign pointers with `__free` attr
in one statement to ensure proper scope-based cleanup

Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/all/aPiG_F5EBQUjZqsl@stanley.mountain/
Signed-off-by: Ally Heev <allyheev@...il.com>
---
 drivers/scsi/scsi_debug.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index b2ab97be5db3d43d5a5647968623b8db72448379..89b36d65926bdd15c0ae93a6bd2ea968e25c0e74 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -2961,11 +2961,11 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
 	int target_dev_id;
 	int target = scp->device->id;
 	unsigned char *ap;
-	unsigned char *arr __free(kfree);
 	unsigned char *cmd = scp->cmnd;
 	bool dbd, llbaa, msense_6, is_disk, is_zbc, is_tape;
 
-	arr = kzalloc(SDEBUG_MAX_MSENSE_SZ, GFP_ATOMIC);
+	unsigned char *arr __free(kfree) = kzalloc(SDEBUG_MAX_MSENSE_SZ, GFP_ATOMIC);
+
 	if (!arr)
 		return -ENOMEM;
 	dbd = !!(cmd[1] & 0x8);		/* disable block descriptors */

---
base-commit: c9cfc122f03711a5124b4aafab3211cf4d35a2ac
change-id: 20251105-aheev-uninitialized-free-attr-scsi-d5f249383404

Best regards,
-- 
Ally Heev <allyheev@...il.com>