Messages in this thread Patch in this message | | | From | Rusty Russell <> | Subject | [PATCH] lguest: fix out-by-one error in address checking. | Date | Wed, 27 May 2015 10:59:26 +0930 |
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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); } /*
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