xsk: Fix out of boundary write in __xsk_rcv_memcpy

first_len is the remainder of the first page we're copying. If this size is larger, then out of page boundary write will otherwise happen. Fixes: c05cd36 ("xsk: add support to allow unaligned chunk placement") Signed-off-by: Li RongQing <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Acked-by: Jonathan Lemon <[email protected]> Acked-by: Björn Töpel <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
jerrinot · Apr 6, 2020 · db5c97f · db5c97f
1 parent 5222d69
commit db5c97f
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
@@ -131,8 +131,9 @@ static void __xsk_rcv_memcpy(struct xdp_umem *umem, u64 addr, void *from_buf,
 		u64 page_start = addr & ~(PAGE_SIZE - 1);
 		u64 first_len = PAGE_SIZE - (addr - page_start);
 
-		memcpy(to_buf, from_buf, first_len + metalen);
-		memcpy(next_pg_addr, from_buf + first_len, len - first_len);
+		memcpy(to_buf, from_buf, first_len);
+		memcpy(next_pg_addr, from_buf + first_len,
+		       len + metalen - first_len);
 
 		return;
 	}