Commit 50b7d856 authored Oct 15, 2020 by Matthew Wilcox (Oracle) Committed by Linus Torvalds Oct 16, 2020

ramfs: fix nommu mmap with gaps in the page cache



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: 642fb4d1 ("[PATCH] NOMMU: Provide shared-writable mmap support on ramfs")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>
Link: https://lkml.kernel.org/r/20200914122239.GO6583@casper.infradead.org


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4d45e75a

fs/ramfs/file-nommu.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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 */

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