| From | lizf@kernel ... | Subject | [PATCH 3.4 113/146] lguest: fix out-by-one error in address checking. | Date | Tue, 15 Sep 2015 17:03:48 +0800 |
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From: Rusty Russell <rusty@rustcorp.com.au>
3.4.109-rc1 review patch. If anyone has any objections, please let me know.
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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: Zefan Li <lizefan@huawei.com> --- 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 b5fdcb7..34842e5 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -171,7 +171,7 @@ 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); } /* -- 1.9.1
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