[PATCH AUTOSEL 6.1 08/10] s390/sclp: Add check for get_zeroed_page()

[PATCH AUTOSEL 6.1 08/10] s390/sclp: Add check for get_zeroed_page()

[Sasha Levin]

From: Haoxiang Li <haoxiang_li2024@163.com>

[ Upstream commit 3db42c75a921854a99db0a2775814fef97415bac ]

Add check for the return value of get_zeroed_page() in
sclp_console_init() to prevent null pointer dereference.
Furthermore, to solve the memory leak caused by the loop
allocation, add a free helper to do the free job.

Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20250218025216.2421548-1-haoxiang_li2024@163.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/s390/char/sclp_con.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/s390/char/sclp_con.c b/drivers/s390/char/sclp_con.c
index e5d947c763ea5..6a030ba38bf36 100644
--- a/drivers/s390/char/sclp_con.c
+++ b/drivers/s390/char/sclp_con.c
@@ -263,6 +263,19 @@ static struct console sclp_console =
 	.index = 0 /* ttyS0 */
 };
 
+/*
+ *  Release allocated pages.
+ */
+static void __init __sclp_console_free_pages(void)
+{
+	struct list_head *page, *p;
+
+	list_for_each_safe(page, p, &sclp_con_pages) {
+		list_del(page);
+		free_page((unsigned long)page);
+	}
+}
+
 /*
  * called by console_init() in drivers/char/tty_io.c at boot-time.
  */
@@ -282,6 +295,10 @@ sclp_console_init(void)
 	/* Allocate pages for output buffering */
 	for (i = 0; i < sclp_console_pages; i++) {
 		page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+		if (!page) {
+			__sclp_console_free_pages();
+			return -ENOMEM;
+		}
 		list_add_tail(page, &sclp_con_pages);
 	}
 	sclp_conbuf = NULL;
-- 
2.39.5

[PATCH AUTOSEL 6.1 09/10] s390/tty: Fix a potential memory leak bug

[Sasha Levin]

From: Haoxiang Li <haoxiang_li2024@163.com>

[ Upstream commit ad9bb8f049717d64c5e62b2a44954be9f681c65b ]

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().

Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20250218034104.2436469-1-haoxiang_li2024@163.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 971fbb52740bf..432dad2a22664 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;
 		}
-- 
2.39.5