From 73424d00dc63ba681856e06cfb0a5abbdb62e2b5 Mon Sep 17 00:00:00 2001
From: Su Hui <suhui@nfschina.com>
Date: Thu, 30 Nov 2023 11:40:18 +0800
Subject: highmem: fix a memory copy problem in memcpy_from_folio

Clang static checker complains that value stored to 'from' is never read.
And memcpy_from_folio() only copy the last chunk memory from folio to
destination.  Use 'to += chunk' to replace 'from += chunk' to fix this
typo problem.

Link: https://lkml.kernel.org/r/20231130034017.1210429-1-suhui@nfschina.com
Fixes: b23d03ef7af5 ("highmem: add memcpy_to_folio() and memcpy_from_folio()")
Signed-off-by: Su Hui <suhui@nfschina.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/highmem.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 4cacc0e43b51..be20cff4ba73 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -454,7 +454,7 @@ static inline void memcpy_from_folio(char *to, struct folio *folio,
 		memcpy(to, from, chunk);
 		kunmap_local(from);
 
-		from += chunk;
+		to += chunk;
 		offset += chunk;
 		len -= chunk;
 	} while (len > 0);
-- 
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