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

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Message-Id: <20200920075722.376644-1-christophe.jaillet@wanadoo.fr>
Date:   Sun, 20 Sep 2020 09:57:22 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     jejb@...ux.ibm.com, martin.petersen@...cle.com, bvanassche@....org,
        jthumshirn@...e.de, hare@...e.com
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] 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 2 years 1/2 old. This
should have been spotted earlier.

So unless this driver is mostly unused, this looks odd to me.
Feedback appreciated.
---
 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 d99568fdf4af..00e155c88f03 100644
--- a/drivers/scsi/pmcraid.c
+++ b/drivers/scsi/pmcraid.c
@@ -3230,8 +3230,9 @@ static struct pmcraid_sglist *pmcraid_alloc_sglist(int buflen)
 		return NULL;
 
 	sglist->order = order;
-	sgl_alloc_order(buflen, order, false,
-			GFP_KERNEL | GFP_DMA | __GFP_ZERO, &sglist->num_sg);
+	sglist->scatterlist = sgl_alloc_order(buflen, order, false,
+					      GFP_KERNEL | GFP_DMA | __GFP_ZERO,
+					      &sglist->num_sg);
 
 	return sglist;
 }
-- 
2.25.1