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Subject[PATCH 2.6.32 25/62] lguest: fix out-by-one error in address checking.
2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Rusty Russell <rusty@rustcorp.com.au>

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.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from commit a8f5259269671acb4f0bdb6e0a53974aa5b351ff)

Signed-off-by: Willy Tarreau <w@1wt.eu>
---
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 8744d24..42ad32c 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -170,7 +170,7 @@ 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);
}

/*
--
1.7.12.2.21.g234cd45.dirty




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