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Patch "lguest: fix out-by-one error in address checking." has been added to the 4.0-stable tree

PATCH [email protected] 1 participant 1 message Jun 3, 2015 Stable branch

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This is a note to let you know that I've just added the patch titled

lguest: fix out-by-one error in address checking.

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
lguest-fix-out-by-one-error-in-address-checking.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 83a35114d0e4583e6b0ca39502e68b6a92e2910c Mon Sep 17 00:00:00 2001

From: Rusty Russell <[email protected]>
Date: Wed, 27 May 2015 10:59:26 +0930
Subject: lguest: fix out-by-one error in address checking.

From: Rusty Russell <[email protected]>

commit 83a35114d0e4583e6b0ca39502e68b6a92e2910c upstream.

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.

---
 drivers/lguest/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/lguest/core.c +1 -1
@@ -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);
 }
 
 /*

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/lguest-fix-out-by-one-error-in-address-checking.patch