From 121fa8198a3fd02b80eacd31fcb49b595304c1c2 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Fri, 10 Mar 2023 08:00:23 +0100
Subject: [PATCH] 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>
---
 mm/swap_state.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/swap_state.c b/mm/swap_state.c
index c7160070b9da..b76a65ac28b3 100644
--- 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))
-- 
2.50.1