netdev - [PATCH] xsk: fix out of boundary write in __xsk_rcv

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Date:   Thu,  2 Apr 2020 15:52:10 +0800
From:   Li RongQing <lirongqing@...du.com>
To:     netdev@...r.kernel.org, bpf@...r.kernel.org, kevin.laatz@...el.com,
        ciara.loftus@...el.com, bruce.richardson@...el.com,
        jonathan.lemon@...il.com, daniel@...earbox.net
Subject: [PATCH] xsk: fix out of boundary write in __xsk_rcv_memcpy

first_len is remainder of first page, if write size is
larger than it, out of page boundary write will happen

Fixes: c05cd3645814 "(xsk: add support to allow unaligned chunk placement)"
Signed-off-by: Li RongQing <lirongqing@...du.com>
---
 net/xdp/xsk.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 356f90e4522b..c350108aa38d 100644
--- 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;
 	}
-- 
2.16.2