2023-09-21 22:39:22

by Brian Geffon

Subject: [PATCH] PM: hibernate: use __get_safe_page() rather than touching the list.

We found at least one situation where the safe pages list was empty and
get_buffer() would gladly try to use a NULL pointer.

Signed-off-by: Brian Geffon <[email protected]>
Fixes: 8357376 ("swsusp: Improve handling of highmem")
Cc: [email protected]

Change-Id: Ibb43a9b4ac5ff2d7e3021fdacc08e116650231e9
---
kernel/power/snapshot.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 362e6bae5891..2dcb33248518 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -2544,8 +2544,9 @@ static void *get_highmem_page_buffer(struct page *page,
pbe->copy_page = pfn_to_page(pfn);
} else {
/* Copy of the page will be stored in normal memory */
- kaddr = safe_pages_list;
- safe_pages_list = safe_pages_list->next;
+ kaddr = __get_safe_page(ca->gfp_mask);
+ if (!kaddr)
+ return ERR_PTR(-ENOMEM);
pbe->copy_page = virt_to_page(kaddr);
}
pbe->next = highmem_pblist;
@@ -2747,8 +2748,9 @@ static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
return ERR_PTR(-ENOMEM);
}
pbe->orig_address = page_address(page);
- pbe->address = safe_pages_list;
- safe_pages_list = safe_pages_list->next;
+ pbe->address = __get_safe_page(ca->gfp_mask);
+ if (!pbe->address)
+ return ERR_PTR(-ENOMEM);
pbe->next = restore_pblist;
restore_pblist = pbe;
return pbe->address;
--
2.42.0.459.ge4e396fd5e-goog

2023-09-22 13:59:32

by Greg KH

Subject: Re: [PATCH] PM: hibernate: use __get_safe_page() rather than touching the list.

On Thu, Sep 21, 2023 at 01:00:45PM -0400, Brian Geffon wrote:
> We found at least one situation where the safe pages list was empty and
> get_buffer() would gladly try to use a NULL pointer.
>
> Signed-off-by: Brian Geffon <[email protected]>
> Fixes: 8357376 ("swsusp: Improve handling of highmem")
> Cc: [email protected]
>
> Change-Id: Ibb43a9b4ac5ff2d7e3021fdacc08e116650231e9

Please always use checkpatch.pl so that maintainers don't have to ask
you to use checkpatch.pl :(