linux-kernel - [PATCH] s390/tty: Fix a potential memory leak bug

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Message-Id: <20250218034104.2436469-1-haoxiang_li2024@163.com>
Date: Tue, 18 Feb 2025 11:41:04 +0800
From: Haoxiang Li <haoxiang_li2024@....com>
To: hca@...ux.ibm.com,
	gor@...ux.ibm.com,
	agordeev@...ux.ibm.com,
	borntraeger@...ux.ibm.com,
	svens@...ux.ibm.com,
	haoxiang_li2024@....com
Cc: linux-s390@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH] s390/tty: Fix a potential memory leak bug

The check for get_zeroed_page() leads to a direct return
and overlooked the memory leak caused by loop allocation.
Add a free helper to free spaces allocated by get_zeroed_page().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@...r.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@....com>
---
 drivers/s390/char/sclp_tty.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/s390/char/sclp_tty.c b/drivers/s390/char/sclp_tty.c
index 892c18d2f87e..99de33694fe3 100644
--- a/drivers/s390/char/sclp_tty.c
+++ b/drivers/s390/char/sclp_tty.c
@@ -490,6 +490,17 @@ static const struct tty_operations sclp_ops = {
 	.flush_buffer = sclp_tty_flush_buffer,
 };
 
+/* Release allocated pages. */
+static void __init __sclp_tty_free_pages(void)
+{
+	struct list_head *page, *p;
+
+	list_for_each_safe(page, p, &sclp_tty_pages) {
+		list_del(page);
+		free_page((unsigned long) page);
+	}
+}
+
 static int __init
 sclp_tty_init(void)
 {
@@ -516,6 +527,7 @@ sclp_tty_init(void)
 	for (i = 0; i < MAX_KMEM_PAGES; i++) {
 		page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 		if (page == NULL) {
+			__sclp_tty_free_pages();
 			tty_driver_kref_put(driver);
 			return -ENOMEM;
 		}
-- 
2.25.1