[PATCH] erofs: fix a potential NULL dereference of alloc_pages()
From: xkernel . wang
Date: Tue Mar 22 2022 - 04:08:54 EST
From: Xiaoke Wang <xkernel.wang@xxxxxxxxxxx>
alloc_pages() returns the page on success or NULL if allocation fails,
while set_page_private() will dereference `newpage`. So it is better to
catch the memory error in case other errors happen.
Signed-off-by: Xiaoke Wang <xkernel.wang@xxxxxxxxxxx>
---
fs/erofs/zdata.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 11c7a1a..36a5421 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -735,11 +735,15 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
struct page *const newpage =
alloc_page(GFP_NOFS | __GFP_NOFAIL);
- set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE);
- err = z_erofs_attach_page(clt, newpage,
- Z_EROFS_PAGE_TYPE_EXCLUSIVE);
- if (!err)
- goto retry;
+ if (!newpage) {
+ err = -ENOMEM;
+ } else {
+ set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE);
+ err = z_erofs_attach_page(clt, newpage,
+ Z_EROFS_PAGE_TYPE_EXCLUSIVE);
+ if (!err)
+ goto retry;
+ }
}
if (err)
--