lguest: fix out-by-one error in address checking.
This bug has been there since day 1; addresses in the top guest physical
page weren't considered valid. You could map that page (the check in
check_gpte() is correct), but if a guest tried to put a pagetable there
we'd check that address manually when walking it, and kill the guest.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 7dc93aa..312ffd3 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -173,7 +173,7 @@
bool lguest_address_ok(const struct lguest *lg,
unsigned long addr, unsigned long len)
{
- return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
+ return addr+len <= lg->pfn_limit * PAGE_SIZE && (addr+len >= addr);
}
/*