FAILED: patch "[PATCH] mtd: docg3: fix use-after-free in docg3_release()" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] mtd: docg3: fix use-after-free in docg3_release()" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x ca19808bc6fac7e29420d8508df569b346b3e339
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026050109-regular-masculine-854d@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ca19808bc6fac7e29420d8508df569b346b3e339 Mon Sep 17 00:00:00 2001
From: James Kim <james010kim@gmail.com>
Date: Mon, 9 Mar 2026 15:05:12 +0900
Subject: [PATCH] mtd: docg3: fix use-after-free in docg3_release()

In docg3_release(), the docg3 pointer is obtained from
cascade->floors[0]->priv before the loop that calls
doc_release_device() on each floor. doc_release_device() frees the
docg3 struct via kfree(docg3) at line 1881. After the loop,
docg3->cascade->bch dereferences the already-freed pointer.

Fix this by accessing cascade->bch directly, which is equivalent
since docg3->cascade points back to the same cascade struct, and
is already available as a local variable. This also removes the
now-unused docg3 local variable.

Fixes: c8ae3f744ddc ("lib/bch: Rework a little bit the exported function names")
Cc: stable@vger.kernel.org
Signed-off-by: James Kim <james010kim@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c
index 33050a2a80f7..603fd0efc2ea 100644
--- a/drivers/mtd/devices/docg3.c
+++ b/drivers/mtd/devices/docg3.c
@@ -2049,7 +2049,6 @@ static int __init docg3_probe(struct platform_device *pdev)
 static void docg3_release(struct platform_device *pdev)
 {
 	struct docg3_cascade *cascade = platform_get_drvdata(pdev);
-	struct docg3 *docg3 = cascade->floors[0]->priv;
 	int floor;
 
 	doc_unregister_sysfs(pdev, cascade);
@@ -2057,7 +2056,7 @@ static void docg3_release(struct platform_device *pdev)
 		if (cascade->floors[floor])
 			doc_release_device(cascade->floors[floor]);
 
-	bch_free(docg3->cascade->bch);
+	bch_free(cascade->bch);
 }
 
 #ifdef CONFIG_OF

[PATCH 5.15.y 1/2] mtd: docg3: Convert to platform remove callback returning void

[Sasha Levin]

From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

[ Upstream commit eb0cec77d534413a800ec20944a2b1e37cfecdcf ]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://lore.kernel.org/linux-mtd/20231008200143.196369-5-u.kleine-koenig@pengutronix.de
Stable-dep-of: ca19808bc6fa ("mtd: docg3: fix use-after-free in docg3_release()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/mtd/devices/docg3.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c
index 27c08f22dec8c..25a7df6448028 100644
--- a/drivers/mtd/devices/docg3.c
+++ b/drivers/mtd/devices/docg3.c
@@ -2038,7 +2038,7 @@ static int __init docg3_probe(struct platform_device *pdev)
  *
  * Returns 0
  */
-static int docg3_release(struct platform_device *pdev)
+static void docg3_release(struct platform_device *pdev)
 {
 	struct docg3_cascade *cascade = platform_get_drvdata(pdev);
 	struct docg3 *docg3 = cascade->floors[0]->priv;
@@ -2050,7 +2050,6 @@ static int docg3_release(struct platform_device *pdev)
 			doc_release_device(cascade->floors[floor]);
 
 	bch_free(docg3->cascade->bch);
-	return 0;
 }
 
 #ifdef CONFIG_OF
@@ -2068,7 +2067,7 @@ static struct platform_driver g3_driver = {
 	},
 	.suspend	= docg3_suspend,
 	.resume		= docg3_resume,
-	.remove		= docg3_release,
+	.remove_new	= docg3_release,
 };
 
 module_platform_driver_probe(g3_driver, docg3_probe);
-- 
2.53.0

[PATCH 5.15.y 2/2] mtd: docg3: fix use-after-free in docg3_release()

[Sasha Levin]

From: James Kim <james010kim@gmail.com>

[ Upstream commit ca19808bc6fac7e29420d8508df569b346b3e339 ]

In docg3_release(), the docg3 pointer is obtained from
cascade->floors[0]->priv before the loop that calls
doc_release_device() on each floor. doc_release_device() frees the
docg3 struct via kfree(docg3) at line 1881. After the loop,
docg3->cascade->bch dereferences the already-freed pointer.

Fix this by accessing cascade->bch directly, which is equivalent
since docg3->cascade points back to the same cascade struct, and
is already available as a local variable. This also removes the
now-unused docg3 local variable.

Fixes: c8ae3f744ddc ("lib/bch: Rework a little bit the exported function names")
Cc: stable@vger.kernel.org
Signed-off-by: James Kim <james010kim@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/mtd/devices/docg3.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c
index 25a7df6448028..7de576404b14f 100644
--- a/drivers/mtd/devices/docg3.c
+++ b/drivers/mtd/devices/docg3.c
@@ -2041,7 +2041,6 @@ static int __init docg3_probe(struct platform_device *pdev)
 static void docg3_release(struct platform_device *pdev)
 {
 	struct docg3_cascade *cascade = platform_get_drvdata(pdev);
-	struct docg3 *docg3 = cascade->floors[0]->priv;
 	int floor;
 
 	doc_unregister_sysfs(pdev, cascade);
@@ -2049,7 +2048,7 @@ static void docg3_release(struct platform_device *pdev)
 		if (cascade->floors[floor])
 			doc_release_device(cascade->floors[floor]);
 
-	bch_free(docg3->cascade->bch);
+	bch_free(cascade->bch);
 }
 
 #ifdef CONFIG_OF
-- 
2.53.0