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....@linaro.org>
---
Just found slow_irqon label is not defined, added it to avoid compile error.
arch/sparc/mm/gup.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index 2e5c4fc..cf4fb47 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
@@ -244,7 +249,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
int write,
slow:
local_irq_enable();
-
+slow_irqon:
/* Try to get the remaining pages with get_user_pages */
start += nr << PAGE_SHIFT;
pages += nr;
--
2.0.2
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