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

[<gregkh@linuxfoundation.org>]

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