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

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

[Haoxiang Li]

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@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.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

Re: [PATCH] s390/tty: Fix a potential memory leak bug

[Heiko Carstens]

On Tue, Feb 18, 2025 at 11:41:04AM +0800, Haoxiang Li wrote:
> 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@vger.kernel.org
> Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
> ---
>  drivers/s390/char/sclp_tty.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)

Same here: no fixes and Cc stable.

Acked-by: Heiko Carstens <hca@linux.ibm.com>

Re: [PATCH] s390/tty: Fix a potential memory leak bug

[Vasily Gorbik]

On Fri, Feb 21, 2025 at 04:13:48PM +0100, Heiko Carstens wrote:
> On Tue, Feb 18, 2025 at 11:41:04AM +0800, Haoxiang Li wrote:
> > 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@vger.kernel.org
> > Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
> > ---
> >  drivers/s390/char/sclp_tty.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> 
> Same here: no fixes and Cc stable.
> 
> Acked-by: Heiko Carstens <hca@linux.ibm.com>

Applied, thank you!