On 02/09/2018 07:24 AM, Arnd Bergmann wrote:
gcc-8 points out that source and destination of the memcpy() are
always the same pointer, so the effect of memcpy() is undefined
here (its arguments must not overlap):

drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c: In function 
drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c:430:2: error: 'memcpy' 
source argument is the same as destination [-Werror=restrict]

Most likely this is harmless, but it's easy to just remove the
line and get rid of the warning.

Signed-off-by: Arnd Bergmann <a...@arndb.de>
  drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c | 1 -
  1 file changed, 1 deletion(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c 
index ac4a82de40c7..9ab56827124e 100644
--- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c
@@ -427,7 +427,6 @@ static void _rtl_rx_process(struct ieee80211_hw *hw, struct 
sk_buff *skb)
                 (u32)hdr->addr1[0], (u32)hdr->addr1[1],
                 (u32)hdr->addr1[2], (u32)hdr->addr1[3],
                 (u32)hdr->addr1[4], (u32)hdr->addr1[5]);
-       memcpy(IEEE80211_SKB_RXCB(skb), rx_status, sizeof(*rx_status));
        ieee80211_rx(hw, skb);

No, the warning is pointing to the wrong place. The routine in question does the following:

1. Loads the rx_status struct from skb->cb.
2. Overwrites the contents with 0.
3. Fills various members of the struct.
4. Writes the revised struct back into skb->cb.

Thus eliminating step 4 negates all the things done in step 3, and is wrong. The correct fix is to change step 1 to create a NULL-filled rx_status struct, and eliminate step 2.



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