From 83a35114d0e4583e6b0ca39502e68b6a92e2910c Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 27 May 2015 10:59:26 +0930 Subject: [PATCH] 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 Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- drivers/lguest/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 7dc93aa004c8..312ffd3d0017 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -173,7 +173,7 @@ static void unmap_switcher(void) 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); } /*