Messages in this thread | | | Date | Tue, 22 Mar 2022 16:28:09 +0800 | From | Gao Xiang <> | Subject | Re: [PATCH] erofs: fix a potential NULL dereference of alloc_pages() |
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On Tue, Mar 22, 2022 at 04:08:12PM +0800, xkernel.wang@foxmail.com wrote: > From: Xiaoke Wang <xkernel.wang@foxmail.com> > > 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@foxmail.com> > --- > 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); >
It's really a nofail allocation, am I missing something?
Thanks, Gao Xiang
> - 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) > --
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