linux-kernel - [PATCH] mtd: rawnand: diskonchip: fix a potential double free in doc

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Date:   Thu, 14 Dec 2023 15:29:43 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mtd: rawnand: diskonchip: fix a potential double free in doc_probe

When nand_scan() fails, it has cleaned up related resources
in its error paths. Therefore, the following nand_cleanup()
may lead to a double-free. One possible trace is:

doc_probe
  |-> nand_scan
  |     |-> nand_scan_with_ids
  |           |-> nand_scan_tail
  |                 |-> kfree(chip->data_buf) [First free]
  |
  |-> nand_cleanup
        |-> kfree(chip->data_buf) [Double free here]

Fix this by removing nand_cleanup() on failure of
nand_scan().

Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
---
 drivers/mtd/nand/raw/diskonchip.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/raw/diskonchip.c b/drivers/mtd/nand/raw/diskonchip.c
index 5d2ddb037a9a..5243fab9face 100644
--- a/drivers/mtd/nand/raw/diskonchip.c
+++ b/drivers/mtd/nand/raw/diskonchip.c
@@ -1491,10 +1491,12 @@ static int __init doc_probe(unsigned long physadr)
 	else
 		numchips = doc2001_init(mtd);
 
-	if ((ret = nand_scan(nand, numchips)) || (ret = doc->late_init(mtd))) {
-		/* DBB note: i believe nand_cleanup is necessary here, as
-		   buffers may have been allocated in nand_base.  Check with
-		   Thomas. FIX ME! */
+	ret = nand_scan(nand, numchips);
+	if (ret)
+		goto fail;
+
+	ret = doc->late_init(mtd);
+	if (ret) {
 		nand_cleanup(nand);
 		goto fail;
 	}
-- 
2.17.1