Commit d3c51c55 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: Fix underflow in gfs2_page_mkwrite 



On filesystems with a block size smaller than PAGE_SIZE and non-empty
files smaller then PAGE_SIZE, gfs2_page_mkwrite could end up allocating
excess blocks beyond the end of the file, similar to fallocate.  This
doesn't make sense; fix it.

Reported-by: default avatarBob Peterson <rpeterso@redhat.com>
Fixes: 184b4e60 ("gfs2: Fix end-of-file handling in gfs2_page_mkwrite")
Cc: stable@vger.kernel.org # v5.5+
Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 38a618db

fs/gfs2/file.c

+2 −2
Original line number Diff line number Diff line
@@ -450,8 +450,8 @@ static vm_fault_t gfs2_page_mkwrite(struct vm_fault *vmf) 
	file_update_time(vmf->vma->vm_file);



	/* page is wholly or partially inside EOF */

	if (offset > size - PAGE_SIZE)

		length = offset_in_page(size);

	if (size - offset < PAGE_SIZE)

		length = size - offset;

	else

		length = PAGE_SIZE;