lguest: fix out-by-one error in address checking.
authorRusty Russell <rusty@rustcorp.com.au>
Wed, 27 May 2015 01:29:26 +0000 (10:59 +0930)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 27 May 2015 16:57:21 +0000 (09:57 -0700)
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>
drivers/lguest/core.c

index 7dc93aa004c86cfa988993d53164ea1d665aff97..312ffd3d00177ca5a5e21393377c760e9bdec91e 100644 (file)
@@ -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);
 }
 
 /*