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.

Fixes: 4c8f4794b61e ("[S390] sclp console: convert from bootmem to slab") Cc: stable@vger.kernel.org Signed-off-by: Haoxiang Li haoxiang_li2024@163.com --- Changes in v2: - Add a free helper to solve the memory leak caused by loop allocation. - Thanks Heiko! I realized that v1 patch overlooked a potential memory leak. After consideration, I choose to do the full exercise. I noticed a similar handling in [1], following that handling I submit this v2 patch. Thanks again!

Reference link: [1]https://github.com/torvalds/linux/blob/master/drivers/s390/char/sclp_vt220.c... --- 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 e5d947c763ea..c87b0c204718 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;