From: Rusty Russell <rusty@rustcorp.com.au>
To: <torvalds@linux-foundation.org>
Cc: <lguest@lists.ozlabs.org>, "LKML" <linux-kernel@vger.kernel.org>
Subject: [PATCH] lguest: fix out-by-one error in address checking.
Date: Wed, 27 May 2015 10:59:26 +0930 [thread overview]
Message-ID: <87ioben6yx.fsf@rustcorp.com.au> (raw)
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
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);
}
/*
reply other threads:[~2015-05-27 1:40 UTC|newest]
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