Commit e4ba4fc2 authored Apr 02, 2013 by Greg Ungerer

romfs: fix nommu map length to keep inside filesystem

Checks introduced in commit 4991e725 ("romfs: do not use
mtd->get_unmapped_area directly") re-introduce problems fixed in the earlier
commit 2b4b2482 ("romfs: fix romfs_get_unmapped_area() argument check").

If a flat binary app is located at the end of a romfs, its page aligned
length may be outside of the romfs filesystem. The flat binary loader, via
nommu do_mmap_pgoff(), page aligns the length it is mmaping. So simple
offset+size checks will fail - returning EINVAL.

We can truncate the length to keep it inside the romfs filesystem, and that
also keeps the call to mtd_get_unmapped_area() happy.

Are there any side effects to truncating the size here though?

Signed-off-by: Greg Ungerer <gerg@uclinux.org>

parent 5143661f

fs/romfs/mmap-nommu.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -49,8 +49,11 @@ static unsigned long romfs_get_unmapped_area(struct file *file,
		return (unsigned long) -EINVAL;

		offset += ROMFS_I(inode)->i_dataoffset;
		if (offset > mtd->size - len)
		if (offset >= mtd->size)
		return (unsigned long) -EINVAL;
		/* the mapping mustn't extend beyond the EOF */
		if ((offset + len) > mtd->size)
		len = mtd->size - offset;

		ret = mtd_get_unmapped_area(mtd, len, offset, flags);
		if (ret == -EOPNOTSUPP)

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