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From: =?UTF-8?q?Carlos=20L=C3=B3pez?= <clopez@suse.de>
To: linux-s390@vger.kernel.org
Cc: =?UTF-8?q?Carlos=20L=C3=B3pez?= <clopez@suse.de>,
	Stefan Haberland <sth@linux.ibm.com>,
	Jan Hoeppner <hoeppner@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Jens Axboe <axboe@kernel.dk>,
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] s390/dasd: fix error checks in dasd_copy_pair_store()
Date: Mon, 27 May 2024 15:50:45 +0200
Message-Id: <20240527135044.27427-1-clopez@suse.de>
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dasd_add_busid() can return an error via ERR_PTR() if an allocation
fails. However, two callsites in dasd_copy_pair_store() do not check
the result, potentially resulting in a NULL pointer dereference. Fix
this by checking the result with IS_ERR() and returning the error up
the stack.

Fixes: a91ff09d39f9b ("s390/dasd: add copy pair setup")
Signed-off-by: Carlos López <clopez@suse.de>
---
 drivers/s390/block/dasd_devmap.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 0316c20823ee..6adaeb985dde 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -2248,13 +2248,19 @@ static ssize_t dasd_copy_pair_store(struct device *dev,
 
 	/* allocate primary devmap if needed */
 	prim_devmap = dasd_find_busid(prim_busid);
-	if (IS_ERR(prim_devmap))
+	if (IS_ERR(prim_devmap)) {
 		prim_devmap = dasd_add_busid(prim_busid, DASD_FEATURE_DEFAULT);
+		if (IS_ERR(prim_devmap))
+			return PTR_ERR(prim_devmap);
+	}
 
 	/* allocate secondary devmap if needed */
 	sec_devmap = dasd_find_busid(sec_busid);
-	if (IS_ERR(sec_devmap))
+	if (IS_ERR(sec_devmap)) {
 		sec_devmap = dasd_add_busid(sec_busid, DASD_FEATURE_DEFAULT);
+		if (IS_ERR(sec_devmap))
+			return PTR_ERR(sec_devmap);
+	}
 
 	/* setting copy relation is only allowed for offline secondary */
 	if (sec_devmap->device)
-- 
2.35.3