[PATCH] sparc64/gup: check address scope legitimacy

[Yang Shi <yang.shi@linaro.org>]

Check if user address is accessible in atomic version __get_user_pages_fast()
before walking the page table.
And, check if end > start in get_user_pages_fast(), otherwise fallback to slow
path.

Signed-off-by: Yang Shi <yang.shi@linaro.org>
---
 arch/sparc/mm/gup.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index 2e5c4fc..08b8da5 100644
--- a/arch/sparc/mm/gup.c
+++ b/arch/sparc/mm/gup.c
@@ -173,6 +173,9 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
+	if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
+					(void __user *)start, len)))
+		return 0;
 
 	local_irq_save(flags);
 	pgdp = pgd_offset(mm, addr);
@@ -203,6 +206,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
+	if (end < start)
+		goto slow_irqon;
 
 	/*
 	 * XXX: batch / limit 'nr', to avoid large irq off latency
-- 
2.0.2