[PATCH] fs: Fix memcpy_sz for remaining count/rwsize

[Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>]

When using memcpy_sz with rwsize != 1 integer division of
count/rwsize may leave some bytes of the request uncopied if
count is not a multiple of rwsize.

Fix this behavior by decrementing count by rwsize instead of
integer division and use plain memcpy for the remaining bytes.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
---
Cc: barebox@lists.infradead.org
---
 fs/fs.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/fs.c b/fs/fs.c
index c041e41bb51b..ccbda22d2692 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -1580,9 +1580,7 @@ static void memcpy_sz(void *dst, const void *src, size_t count, int rwsize)
 
 	rwsize = rwsize >> O_RWSIZE_SHIFT;
 
-	count /= rwsize;
-
-	while (count-- > 0) {
+	while (count > 0) {
 		switch (rwsize) {
 		case 1:
 			*((u8 *)dst) = *((u8 *)src);
@@ -1599,7 +1597,12 @@ static void memcpy_sz(void *dst, const void *src, size_t count, int rwsize)
 		}
 		dst += rwsize;
 		src += rwsize;
+		count -= rwsize;
 	}
+
+	/* copy remaining bytes with plain memcpy */
+	if (count)
+		memcpy(dst, src, count);
 }
 
 ssize_t mem_read(struct cdev *cdev, void *buf, size_t count, loff_t offset, ulong flags)
-- 
2.1.0


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