r8169: fix potential skb double free in an error path

The caller of rtl8169_tso_csum_v2() frees the skb if false is returned. eth_skb_pad() internally frees the skb on error what would result in a double free. Therefore use __skb_put_padto() directly and instruct it to not free the skb on error. Fixes: b423e9a ("r8169: fix offloaded tx checksum for small packets.") Reported-by: Jakub Kicinski <[email protected]> Signed-off-by: Heiner Kallweit <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
akvadrako · Nov 7, 2020 · cc6528b · cc6528b
1 parent 86bbf01
commit cc6528b
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4163,7 +4163,8 @@ static bool rtl8169_tso_csum_v2(struct rtl8169_private *tp,
 		opts[1] |= transport_offset << TCPHO_SHIFT;
 	} else {
 		if (unlikely(skb->len < ETH_ZLEN && rtl_test_hw_pad_bug(tp)))
-			return !eth_skb_pad(skb);
+			/* eth_skb_pad would free the skb on error */
+			return !__skb_put_padto(skb, ETH_ZLEN, false);
 	}
 
 	return true;