linux-kernel - [PATCH v2] scsi: pmcraid: Fix memory allocation in 'pmcraid_alloc

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Date:   Mon, 10 Jan 2022 13:02:53 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     hch@....de, "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Bart Van Assche <bvanassche@....org>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Hannes Reinecke <hare@...e.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-scsi@...r.kernel.org
Subject: [PATCH v2] scsi: pmcraid: Fix memory allocation in 'pmcraid_alloc_sglist()'

When the scatter list is allocated in 'pmcraid_alloc_sglist()', the
corresponding pointer should be stored in 'scatterlist' within the
'pmcraid_sglist' structure. Otherwise, 'scatterlist' is NULL.

This leads to a potential memory leak and NULL pointer dereference.

Fixes: ed4414cef2ad ("scsi: pmcraid: Use sgl_alloc_order() and sgl_free_order()")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
This patch is completely speculative and untested.

Should it be correct, I think that their should be some trouble somewhere.
Either NULL pointer dereference or incorrect behavior.
The patch that introduced this potential bug is from 2018-02. So, this
should have been spotted earlier.

So unless this driver is mostly unused, this looks odd to me.
Feedback appreciated.

Review with care!

v2: synch with -next-20220110
---
 drivers/scsi/pmcraid.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/pmcraid.c b/drivers/scsi/pmcraid.c
index 928532180d32..e314ea133827 100644
--- a/drivers/scsi/pmcraid.c
+++ b/drivers/scsi/pmcraid.c
@@ -3221,8 +3221,9 @@ static struct pmcraid_sglist *pmcraid_alloc_sglist(int buflen)
 		return NULL;
 
 	sglist->order = order;
-	sgl_alloc_order(buflen, order, false, GFP_KERNEL | __GFP_ZERO,
-			&sglist->num_sg);
+	sglist->scatterlist = sgl_alloc_order(buflen, order, false,
+					      GFP_KERNEL | __GFP_ZERO,
+					      &sglist->num_sg);
 
 	return sglist;
 }
-- 
2.32.0