2023-11-30 03:40:55

by Su Hui

Subject: [PATCH] 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.
Using 'to += chunk' to replace 'from += chunk' to fix this typo problem.

Fixes: b23d03ef7af5 ("highmem: add memcpy_to_folio() and memcpy_from_folio()")
Signed-off-by: Su Hui <[email protected]>
---
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);
--
2.30.2

2023-11-30 04:16:25

by Matthew Wilcox

Subject: Re: [PATCH] highmem: fix a memory copy problem in memcpy_from_folio

On Thu, Nov 30, 2023 at 11:40:18AM +0800, Su Hui wrote:
> 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.
> Using 'to += chunk' to replace 'from += chunk' to fix this typo problem.
>
> Fixes: b23d03ef7af5 ("highmem: add memcpy_to_folio() and memcpy_from_folio()")
> Signed-off-by: Su Hui <[email protected]>

Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>