[PATCH AUTOSEL 5.15 6/8] s390/sclp: Add check for get_zeroed_page()

[Sasha Levin <sashal@kernel.org>]

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 de028868c6f4a..4e5d5da258d68 100644
--- a/drivers/s390/char/sclp_con.c
+++ b/drivers/s390/char/sclp_con.c
@@ -260,6 +260,19 @@ 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.
  */
@@ -279,6 +292,10 @@ 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