[PATCH 2.6.32 25/62] lguest: fix out-by-one error in address checking.

[Willy Tarreau]

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

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

From: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
(cherry picked from commit a8f5259269671acb4f0bdb6e0a53974aa5b351ff)

Signed-off-by: Willy Tarreau <w@xxxxxx>
---
 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



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/