mtd: rawnand: atmel: Fix possible memory leak

BugLink: https://bugs.launchpad.net/bugs/2101915

[ Upstream commit 6d734f1bfc336aaea91313a5632f2f197608fadd ]

The pmecc "user" structure is allocated in atmel_pmecc_create_user() and
was supposed to be freed with atmel_pmecc_destroy_user(), but this other
helper is never called. One solution would be to find the proper
location to call the destructor, but the trend today is to switch to
device managed allocations, which in this case fits pretty well.

Replace kzalloc() by devm_kzalloc() and drop the destructor entirely.

Reported-by: "Dr. David Alan Gilbert" <linux@treblig.org>
Closes: https://lore.kernel.org/all/ZvmIvRJCf6VhHvpo@gallifrey/
Fixes: f88fc12 ("mtd: nand: Cleanup/rework the atmel_nand driver")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20241001203149.387655-1-miquel.raynal@bootlin.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: miquelraynal

drivers/mtd/nand/raw/atmel/pmecc.c

@@ -362,7 +362,7 @@ atmel_pmecc_create_user(struct atmel_pmecc *pmecc,
 	size = ALIGN(size, sizeof(s32));
 	size += (req->ecc.strength + 1) * sizeof(s32) * 3;
 
-	user = kzalloc(size, GFP_KERNEL);
+	user = devm_kzalloc(pmecc->dev, size, GFP_KERNEL);
 	if (!user)
 		return ERR_PTR(-ENOMEM);
 
@@ -408,12 +408,6 @@ atmel_pmecc_create_user(struct atmel_pmecc *pmecc,
 }
 EXPORT_SYMBOL_GPL(atmel_pmecc_create_user);
 
-void atmel_pmecc_destroy_user(struct atmel_pmecc_user *user)
-{
-	kfree(user);
-}
-EXPORT_SYMBOL_GPL(atmel_pmecc_destroy_user);
-
 static int get_strength(struct atmel_pmecc_user *user)
 {
 	const int *strengths = user->pmecc->caps->strengths;

drivers/mtd/nand/raw/atmel/pmecc.h

@@ -55,8 +55,6 @@ struct atmel_pmecc *devm_atmel_pmecc_get(struct device *dev);
 struct atmel_pmecc_user *
 atmel_pmecc_create_user(struct atmel_pmecc *pmecc,
 			struct atmel_pmecc_user_req *req);
-void atmel_pmecc_destroy_user(struct atmel_pmecc_user *user);
-
 void atmel_pmecc_reset(struct atmel_pmecc *pmecc);
 int atmel_pmecc_enable(struct atmel_pmecc_user *user, int op);
 void atmel_pmecc_disable(struct atmel_pmecc_user *user);