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

Sasha Levin
2025-04-04T00:07:44Z

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