[PATCH 4.9 008/141] parisc: Fix map_pages() to not overwrite existing pte entries

Greg Kroah-Hartman
2018-11-11T22:46:30Z

From: Helge Deller <deller@gmx.de>

commit 3c229b3f2dd8133f61bb81d3cb018be92f4bba39 upstream.

Fix a long-existing small nasty bug in the map_pages() implementation which
leads to overwriting already written pte entries with zero, *if* map_pages() is
called a second time with an end address which isn't aligned on a pmd boundry.
This happens for example if we want to remap only the text segment read/write
in order to run alternative patching on the code. Exiting the loop when we
reach the end address fixes this.

Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/parisc/mm/init.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -491,12 +491,8 @@ static void __init map_pages(unsigned lo
pte = pte_mkhuge(pte);
}

- if (address >= end_paddr) {
- if (force)
- break;
- else
- pte_val(pte) = 0;
- }
+ if (address >= end_paddr)
+ break;

set_pte(pg_table, pte);