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romfs: fix nommu map length to keep inside filesystem 

Checks introduced in commit 4991e7251 ("romfs: do not use
mtd->get_unmapped_area directly") re-introduce problems fixed in the earlier
commit 2b4b2482e ("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>
This commit is contained in:
Greg Ungerer 2013-04-02 14:25:33 +10:00
parent 5143661ff8
commit e4ba4fc2b9
1 changed files with 4 additions and 1 deletions
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5
fs/romfs/mmap-nommu.c
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@ -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)