[PATCH 5.9 511/757] ramfs: fix nommu mmap with gaps in the page cache

[Greg Kroah-Hartman]

From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

[ Upstream commit 50b7d85680086126d7bd91dae81d57d4cb1ab6b7 ]

ramfs needs to check that pages are both physically contiguous and
contiguous in the file.  If the page cache happens to have, eg, page A for
index 0 of the file, no page for index 1, and page A+1 for index 2, then
an mmap of the first two pages of the file will succeed when it should
fail.

Fixes: 642fb4d1f1dd ("[PATCH] NOMMU: Provide shared-writable mmap support on ramfs")
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200914122239.GO6583@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/ramfs/file-nommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index 4146954549560..355523f4a4bf3 100644
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -224,7 +224,7 @@ static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
 	if (!pages)
 		goto out_free;
 
-	nr = find_get_pages(inode->i_mapping, &pgoff, lpages, pages);
+	nr = find_get_pages_contig(inode->i_mapping, pgoff, lpages, pages);
 	if (nr != lpages)
 		goto out_free_pages; /* leave if some pages were missing */
 
-- 
2.25.1