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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Lv Yunlong <lyl2019@mail.ustc.edu.cn>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 119/188] ethernet: myri10ge: Fix a use after free in myri10ge_sw_tso
Date:   Mon, 12 Apr 2021 10:40:33 +0200
Message-Id: <20210412084017.609447378@linuxfoundation.org>
In-Reply-To: <20210412084013.643370347@linuxfoundation.org>
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From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>

[ Upstream commit 63415767a2446136372e777cde5bb351f21ec21d ]

In myri10ge_sw_tso, the skb_list_walk_safe macro will set
(curr) = (segs) and (next) = (curr)->next. If status!=0 is true,
the memory pointed by curr and segs will be free by dev_kfree_skb_any(curr).
But later, the segs is used by segs = segs->next and causes a uaf.

As (next) = (curr)->next, my patch replaces seg->next to next.

Fixes: 536577f36ff7a ("net: myri10ge: use skb_list_walk_safe helper for gso segments")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/myricom/myri10ge/myri10ge.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
index 1634ca6d4a8f..c84c8bf2bc20 100644
--- a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
+++ b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
@@ -2897,7 +2897,7 @@ static netdev_tx_t myri10ge_sw_tso(struct sk_buff *skb,
 			dev_kfree_skb_any(curr);
 			if (segs != NULL) {
 				curr = segs;
-				segs = segs->next;
+				segs = next;
 				curr->next = NULL;
 				dev_kfree_skb_any(segs);
 			}
-- 
2.30.2