linux-kernel - [PATCH] uio: fix is_source param for check_copy_size() in copy_to_iter

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Date:   Wed, 05 Sep 2018 13:31:40 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     gregkh@...uxfoundation.org
Cc:     dan.j.williams@...el.com, vishal.l.verma@...el.com,
        fan.du@...el.com, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] uio: fix is_source param for check_copy_size() in
 copy_to_iter_mcsafe()

copy_to_iter_mcsafe() is passing in the is_source parameter as "false"
to check_copy_size(). This is different than what copy_to_iter() does.
Also, the addr parameter passed to check_copy_size() is the source so
therefore we should be passing in "true" instead.

Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()")

Reported-by: Fan Du <fan.du@...el.com>
Signed-off-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Vishal Verma <vishal.l.verma@...el.com>
---
 include/linux/uio.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 409c845d4cd3..422b1c01ee0d 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -172,7 +172,7 @@ size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 static __always_inline __must_check
 size_t copy_to_iter_mcsafe(void *addr, size_t bytes, struct iov_iter *i)
 {
-	if (unlikely(!check_copy_size(addr, bytes, false)))
+	if (unlikely(!check_copy_size(addr, bytes, true)))
 		return 0;
 	else
 		return _copy_to_iter_mcsafe(addr, bytes, i);