mm-return-an-err_ptr-from-__filemap_get_folio-fix

fix null-pointer deref

Link: https://lkml.kernel.org/r/20230310070023.GA13563@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Link: https://lkml.kernel.org/r/20230310043137.GA1624890@u2004
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/swap_state.c b/mm/swap_state.c
index c7160070b9daa93a6cf6400b7c5d3e2d5a7e1f9e..b76a65ac28b319ca2a73b33a430a0195e8584b62 100644 (file)
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -390,6 +390,8 @@ struct folio *filemap_get_incore_folio(struct address_space *mapping,
        struct swap_info_struct *si;
        struct folio *folio = filemap_get_entry(mapping, index);
 
+       if (!folio)
+               return ERR_PTR(-ENOENT);
        if (!xa_is_value(folio))
                return folio;
        if (!shmem_mapping(mapping))